I recently revisited a book I enjoyed: The Blue Machine by physicist, oceanographer, and writer Helen Czerski. It is a beautifully clear exploration of the deep mechanics of the ocean and why those processes are so essential to keeping our planet cool, biodiverse, and stable.
One of the core ideas she returns to is ocean upwelling, a process that is especially important for those of us who live in California. Upwelling is one of those hidden forces that quietly underlies everything around us, and once you read about it, you realize that so much of what we know and love here simply would not exist without it.
Few marine processes are as impactful on the abundance of sea life off the coast of California as upwelling. It may not be a term you’ve heard before, but the natural oceanic process of upwelling is one of the most important engines driving climate, biological diversity, and the ocean’s food web.
It’s time to pay attention.
The abundance of sea life around some of California’s oil rigs is due in part to ocean upwelling near the continental shelf. (Photo: Erik Olsen)
In simple terms, upwelling is when cold, nutrient-rich water from the deep ocean rises to the surface, replacing warmer surface water. A churn. Along the California coast, prevailing northerly winds push surface waters offshore through the Coriolis effect, allowing deeper, colder water to rise in their place. Over the continental shelf off shore California, this upwelled water is rapidly brought into shallower depths, delivering nutrients directly into the photic zone where phytoplankton can grow. This is one reason continental shelves, including areas around offshore oil platforms (which I wrote about a few weeks ago), are biological hotspots.
California’s upwelling system is one of the most intensively studied in the world because it fuels the region’s crazy marine productivity.
In California, upwelling occurs year-round off the northern and central coast. It’s strongest in the spring and summer when northwesterly winds are at their most powerful. Upwelling is reduced in the fall and winter when winds are more variable.
Killer whales benefit from upwelling because the nutrient-rich waters fuel a surge in phytoplankton, which triggers an increase in the populations of smaller prey fish and marine mammals that orcas rely on for sustenance. (Photo: NOAA)
Researchers from institutions like the Scripps Institution of Oceanography and Stanford University have used a variety of methods, including satellite observations and computer modeling, to study upwelling. One of the groundbreaking studies was the CalCOFI program (California Cooperative Oceanic Fisheries Investigations), which began in the late 1940s. It was a joint venture between Scripps and state and federal agencies to investigate the collapse of the sardine fishery. The study showed that the sardine collapse was not just due to overfishing but also large-scale ocean and climate variability, a finding that reshaped fisheries science. Over decades, it has expanded its scope and now provides invaluable long-term datasets that help scientists understand upwelling and its impacts on marine populations.
Deep, cold ocean water is rich in nutrients because organic matter from the surface sinks as it dies or is consumed, and is broken down at depth, releasing nutrients back into the water. When that water is brought to the surface through upwelling, it delivers a fresh supply of nutrients that fuels phytoplankton growth and supports the entire marine food web.
The food web is kind of like a ladder. Or a chain. Nutrient-rich cold waters support blooms of phytoplankton: microscopic, photosynthetic organisms (meaning they are teeming with chlorophyll) that produce oxygen and form the base of marine food webs. When these primary producers flourish, it triggers a chain reaction throughout the ecosystem: zooplankton feed on phytoplankton, small fish feed on zooplankton, and larger predators, including fish, marine mammals, seabirds, (and humans) reap the rewards! So a well functioning upwelling system is pretty important for abundant sea life.
Also, cold water holds more dissolved gases like oxygen compared to warm water (yet another reason that warming seas could be a problem in the future). Oxygen is crucial for marine animals. In cold, oxygen-rich environments, organisms can efficiently carry out metabolic processes, which leads to higher rates of feeding, growth, and reproduction, thereby further boosting biological productivity. Everyone wins!
But there’s a problem.
Sardines off the coast of California (Photo: NOAA)
Studies have shown that natural changes in climate, like El Niño and La Niña events have a significant impact on wildlife and the local ocean ecosystem. During El Niño events, warmer waters and weaker upwelling reduce nutrient levels in the California Current, lowering phytoplankton productivity and causing deadly ripples through the food web. La Niña conditions generally strengthen upwelling, bringing nutrient-rich water to the surface and boosting marine productivity.
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Climate change adds a potentially dangerous new layer of uncertainty: oceans are warming and growing more acidic, which can disrupt the timing, strength, and benefits of upwelling. While climate change does not necessarily mean more El Niño years, it does mean that El Niño events now play out in a warmer ocean, often amplifying their impacts and increasing stress on marine life, with serious consequences for some organisms.
Sea lions off the Southern California coast. (Photo: Erik Olsen)
We’ve been seeing some of these impacts. Take sea lions and large fish populations. In years of strong upwelling, prey is more abundant and closer to shore, allowing California sea lions to forage more efficiently and increasing populations. During weak upwelling years, prey becomes scarcer and more dispersed, forcing sea lions to travel farther for food, increasing stress and reducing reproductive success. Variations like this have been observed in recent years during El Niño periods along the California coast, showing how quickly marine ecosystems respond to shifts in ocean conditions.
Of course, upwelling isn’t just a California thing; it’s a global phenomenon that occurs in various parts of the world, from the coasts of Peru to the Canary Islands. It serves a similar churning life inducing function in these places, too. But California is sort of the poster child for scientists thanks to extensive research here and its vital role in a multi-billion dollar fishing industry that includes species like albacore tuna, swordfish, Dungeness crab, squid, and sardines.
Anacaps Island in California’s Channel Islands (Photo: Erik Olsen)
Upwelling is one of those critical oceanic processes that helps maintain our stable and immensely productive California waters, but warming ocean temperatures and changes in wind patterns could cause big problems, disrupting the timing and intensity of upwelling, putting sea life off California’s coast at risk.
Of course, I do not mean for this piece to be yet another downer about climate change. California’s coastal ecosystem is, in many ways, healthier today than it has been in decades, thanks to policies and practices put in place once we began to understand what was truly at stake. Whenever I get offshore and experience the ocean firsthand, I feel deeply grateful for what we have now, even as I remain aware that it is something we could still damage if we’re stupid and careless…which is not out of the question. The encouraging part is that Californians have shown, again and again, a real capacity to rally when it matters. For now, then, it is worth appreciating what we have and getting out there to experience it whenever you get the chance.
If I told you that some of the richest, densest communities of marine life anywhere in the world thrive off California, you might not be surprised. We all know California has a vibrant marine ecosystem offshore. But if I told you that much of that life clings to the submerged steel legs of offshore oil rigs, you might pause, blink, and say: really?
The answer is yes.
I know because I have dived a few of them several times. Most recently this November, when I took a dive boat called the Giant Stride out of San Pedro and motored 12 miles out to the Eureka platform, which sits in 700 feet of water. From the deck, the rig looms like a floating city of steel and shadow, its massive pylon legs disappearing into the depths below.
The Eureka oil rig off the coast of California from the Giant Stride dive boat. An industrial behemoth above water, beneath, it is home to an immense diversity of sea life. (Photo: Erik Olsen)
But below the surface is another world, one teeming with millions of colorful fish, including blazing orange garibaldi, schools of dark blue blacksmiths, halfmoons, calico bass, yellowtail, and even the occasional mola mola or sunfish. A few rigs are the playground of scores of jubilant sea lions, many of them precocious youngsters that swoop and spin in the waters beneath the massive structure of the rigs like children let loose in a grassy park.
Playful sea lions frolic around the rigs beneath the surface. (Photo: Erik Olsen)
And then there are the pylons themselves and the life they support. Made of welded steel, these massive structures hold the entire oil platform above the water, millions of tons of machinery and deck space, often topped by a helicopter pad, all balanced on the integrity of engineering. Some descend straight down into the darkening waters, while others are reinforced by diagonal braces and horizontal crossbeams, a lattice of intersecting steel that keeps the rig steady against waves and wind.
But up close, you can hardly make out the metal. The substructure is so encrusted with life, layers of scallops, brittle stars, mussels, anemones, barnacles, and sponges, that the steel beneath has vanished into a living reef. In some areas, there are thousands of brittle stars clinging to the structure, they lie so thick on it that it’s hard to imagine how they compete for food. But food here is plentiful, and that abundance is one reason these rigs harbor so much life. They stand near the edge of the continental shelf, where the seafloor plunges into deeper water and cold, nutrient-rich currents surge upward toward the light. Those nutrients ignite blooms of plankton, feeding swarms of tiny crustaceans and filter feeders that coat the rig’s pilings. Those smaller creatures, in turn, sustain fish, sea lions, and even passing seabirds, a food web in full expression, built around the steel spine of an oil platform.
Brittle stars, mussels and other oprganisms blanket the rig supports in incredible numbers. (Photo: Erik Olsen)
All of this is not just my observation, however. Numerous studies have been done about the life on the rigs and most of them point to an astonishing fact: these rigs are some of the most productive ecosystems on the planet. In one study, University of California Santa Barbara marine biologist Milton Love and his colleagues found that certain platforms, including Eureka, produced more fish biomass per square meter than even the most productive natural environments in the world. More than mangroves, coral reefs, estuaries, etc.
The Eureka rig off the coast of Southern California. Once built to pump oil, it’s now also home to sea lions, fish, and a reef of life growing on its legs below the waves. (Photo: Erik Olsen)
This is good news for everyone. But there’s more. Other research suggests that the life flourishing on these offshore rigs doesn’t stay confined to them; it drifts, swims, and spawns its way back toward the coast, helping to replenish nearshore habitats. Rockfish are a perfect example. Once severely overfished, several species have made a remarkable comeback in California waters, perhaps due in part to these structures. As we wrote recently, the recovery of rockfish is one of the state’s quiet success stories.
But there’s a hitch.
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Several of these rigs are now nearing, or have already reached, the end of their productive lifespan, meaning that they no longer produce much oil. What should be done with them? In California, when offshore oil rigs reach the end of their productive life, state law mandates their decommissioning, which involves safely plugging wells, dismantling structures, and restoring the environment. Traditionally, this has meant full removal of the platform and associated infrastructure: a very expensive proposition, likely costing in the billions of dollars.
Clusters of mussels and strawberry anemones (Corynactis californica) coat the rig’s submerged structure in a dense mosaic of color. They form living carpets over the steel, while mussels, bryozoans, and brittle stars fill the gaps between them. (Photo: Erik Olsen)
However, the California Marine Resources Legacy Act (AB 2503), enacted in 2010, introduced an alternative known as the “rigs-to-reefs” program. This legislation allows oil companies to apply for permits to partially remove decommissioned rigs, essentially shearing off the part of the structure above water and leaving a portion of it underwater to serve as artificial reefs. Obviously they’d do it deep enough, about 80 feet, that the structure would not become a hazard to ship traffic. The goal is to enhance marine habitats by preserving the ecosystems that have developed around these structures over time. Rig removal is a growing billion-dollar-a-year business, and by removing only part of the rig and leaving behind the rest, an oil company can save millions in decommissioning costs.
As of January 2024, there are eight offshore production platforms in various stages of decommissioning; several have had multiple owners and operators. It’s complicated, but the biggest issue is liability. That is, what happens down the line when there is a leak, or if the plugging of the wells was done improperly? Who pays for that? This is all being hashed out, as it has been for some 20 years now. Californians hate oil washing up on their beaches. Many hate the idea of the oil companies getting a financial break after plundering the sea floor for oil. But there is no denying that all that life is there. You can see it. And, as Milton Love said: “If you remove a platform, you may be killing tens of millions of animals because they happened to settle on steel instead of a rock. Which I think is a tragedy.”
Substructure of the Eureka rig above water in California (Erik Olsen)
Oil companies have not used California’s Rigs-to-Reefs law because it leaves them financially and legally burdened. They must keep long-term liability for the structures and give up to 80 percent of their cost savings to the state, which makes full removal simpler and less risky than the complex and politically sensitive reefing process.
And so, as some of these platforms near the end of their productive lives, a significant debate has emerged over their future. Should they be removed entirely, or could they be repurposed into artificial reefs that continue to support marine biodiversity? The discussion is not just about engineering challenges or environmental concerns; it’s about reimagining the relationship between human infrastructure and the natural world.
Amber Sparks led the expedition I took out to the rigs. I’ve dived with her several times before and believe she’s a passionate advocate for sea life and for a healthy offshore California marine ecosystem. She and her co-founder Emily Hazelwood are strong supporters of reefing the rigs, and through their work with Blue Latitudes, they collaborates with scientists, government agencies, and oil companies to explore ways decommissioned platforms could be transformed into permanent marine habitats rather than dismantled and removed.
“The big question is, are these structures good habitat that should be left in place to continue to thrive as reefs, or should they be removed? In my opinion, they would be really valuable to be left in place as reefs.”
A brittle star falls through the water column beneath the Eureka rig (Erik Olsen)
So where do things stand today? A December 2023 Public Environmental Impact Statement (PEIS) from the Bureau of Safety and Environmental Enforcement and Bureau of Ocean Energy Management marks the most recent major development in the offshore rig debate, and it could significantly shape future decommissioning of California’s oil platforms. Though the PEIS identifies partial removal as the environmentally preferable option (italics mine) because it would preserve the habitat of existing biological communities, the agencies involved selected “Alternative 1a”, mandating complete removal of platform jackets and associated infrastructure offshore southern California. The final decision over what to do with the rigs has not yet been made, but the current wisdom suggests that they may have to go. As a diver and novice fisherman, I consider this a shame.
Public opposition to “big oil” remains strong in California, fueling demands among small but vocal groups for the complete removal of oil rigs, despite the potential loss of coral-like ecosystems. Environmental groups like the Natural Resources Defense Council argue that retaining any portion of these structures enables the oil industry to persist as an environmental threat.
Beneath the surface of a California oil rig, a vibrant colony of pink strawberry anemones transforms industrial infrastructure into an underwater oasis. (Erik Olsen)
“People here have been waiting for these oil platforms to go away,” Linda Krop, an environmental lawyer with the Environmental Defense Center, an advocacy group based in Santa Barbara, told the me when I reported on this for the New York Times. Ms. Krop challenged the notion that the science definitively supports the role of rigs in fostering marine life. She argued that leaving the rigs in place would effectively reward polluters by allowing them to avoid the expense of removal.
Globally, the concept of Rigs-to-Reefs has seen success, particularly in the Gulf of Mexico, where over 500 platforms have been converted into artificial reefs. These structures have become magnets for fish and invertebrates, supporting commercial and recreational fishing and diving industries. However, critics argue that not all programs are created equal. In some regions, lax regulations have allowed oil companies to avoid fully addressing environmental risks, leaving behind structures that degrade over time and release pollutants. California’s approach, with its stringent oversight and commitment to environmental benefits, aims to avoid these pitfalls while maximizing ecological gains.
The oil rigs substructure provides a fascinating contrast to the life on large sections of it. (Erik Olsen)
What happens to California’s oil platforms will reveal how the state chooses to balance economic legacy with ecological responsibility. Few would argue that oil companies deserve further rewards after decades of drilling and profits, yet the decision ahead is not so simple, it is about what becomes of the ecosystems that have grown around their steel foundations. There should be a way to move forward responsibly, one that removes the risk and legacy of drilling while preserving the thriving marine life that has made these structures their home.
You can scroll endlessly through TikTok and Instagram for quick bursts of California’s beauty, but to truly sink into a subject, and to savor the craft of a great writer, you need a book. I’m an avid reader, and over the past decade I’ve dedicated a large section of my bookshelf to books about California: its wild side, its nature, and its scientific wonders.
There are surely many other books that could be included in this top ten list, but these are the finest I’ve come across in the years since returning to live in the state.They capture the extraordinary diversity of California’s landscapes and wildlife, found nowhere else on Earth, and many also explore issues and themes that hold deep importance for the state and its people. Although I’ve read some of these titles digitally, I love having many of them in print, because there are few things more satisfying than settling into a beach, a forest campsite, or a favorite chair at home with a beautifully made book in hand.
I first discovered Rosanna Xia’s work through her stunning exposé on the thousands of DDT barrels found dumped on the seafloor near Catalina Island. It remains one of the most shocking, and yet not technically illegal, environmental scandals in California’s history.
Her recent book, California Against the Sea: Visions for Our Vanishing Coastline, is a beautifully written and deeply reported look at how California’s coastal communities are confronting the realities of climate change and rising seas. Xia travels the length of the state, from Imperial Beach to Pacifica, weaving together science, policy, and personal stories to show how erosion, flooding, and climate change are already reshaping lives. What makes the book stand out is its relative balance; it’s not a screed, nor naïvely hopeful. It nicely captures the tension between human settlement — our love and need to be near the ocean — and the coast’s natural (and unnatural, depending on how you look at it) cycles of change.
Xia is at her best when exploring adaptation and equity. She reminds us that even if emissions stopped today, the ocean will keep rising, and that not all communities have equal means to respond. The stories of engineers, Indigenous leaders, and ordinary residents highlight how resilience and adaptation must be rooted in local realities. I was especially drawn to Xia’s account of the California Coastal Commission, a wildly controversial agency that wields immense power over the future of the shoreline. Yet it was the commission and its early champions, such as Peter Douglas, who ensured that California’s coast remained open and accessible to all, a decision I consider one of the greatest legislative achievements in modern conservation history.
Thoughtful, accessible, and rooted in the coast we all care about, California Against the Sea challenges us to ask a pressing question: how can we live wisely, and with perspective, at the edge of a changing world?
Kim Stanley Robinson’s The High Sierra: A Love Story is an expansive, heartfelt tribute to California’s most iconic mountain range. Because of the Sierra’s vast internal basins, which are missing from many of the world’s other great mountain ranges, Robinson argues they are among the best mountains on Earth. His point is hard to refute. He makes a convincing case that the Sierra Nevada may be the greatest range in the world, formed from the planet’s largest single block of exposed granite and lifted over millions of years into its dramatic present shape.
Blending memoir, geology (my favorite part of the book), and adventure writing, Robinson chronicles his own decades of exploration in the Sierra Nevada while tracing the forces — glacial, tectonic, and emotional, that shaped both the landscape and his own life.
Considered one of our greatest living science fiction writers (I’ve read Red Mars — long, but superb — and am currently reading The Ministry for the Future — the opening chapter is gripping and terrifying), Robinson might seem an unlikely guide to the granite heights of California. Yet reading The High Sierra: A Love Story reveals how naturally his fascination with imagined worlds extends into this very real one. The drama of the range, with its light, vastness, and sculpted peaks and basins, feels like raw material for his other universes.
The Dreamt Land is a portrait of California’s Central Valley, where the control of water has defined everything from landscape to power (power in the form of hydroelectric energy and human control over who gets to shape and profit from the valley’s vast resources). Blending investigative journalism, history, and memoir, Arax explores how the state’s rivers, dams, and aqueducts turned desert into farmland and how that transformation came at immense ecological and social cost.
I’ve read several Arax books, but this one is my favorite. He’s one of the finest writers California has produced. He writes with passion and clarity, grounding his ideas in decades of firsthand experience with California’s land and water. His focus on the fertile Central Valley, where he grew up as a reporter and farmer’s son, gives the book both intimacy and authority, revealing how decisions about water shape not just the landscape but the people who depend on it. There are heroes and villains, plenty of the latter, and all of them unmistakably real. Yet Arax’s prose is so fluid and eloquent that you’ll keep reading not only for the story, but for the sheer pleasure of his writing.
If you’re at all fascinated by California’s wild geology — and it truly is wild, just ask any geologist — this classic from one of the finest nonfiction writers alive is a must-read. McPhee takes readers on a geological road-trip through California, from the uplifted peaks of the Sierra Nevada to the fault-riven terrain of the San Andreas zone. He teams up with UC Davis geologist Eldridge Moores to explain how oceanic plates, island arcs, and continental blocks collided over millions of years to “assemble” the landmass we now call California. His prose is classic McPhee: clean, vivid, perhaps sometimes overly technical, as he turns terms like “ophiolite” and “batholith” into aspects of a landscape you can picture and feel.
What makes the book especially rewarding, especially for someone interested in earth systems, mapping, and the deep time, is how McPhee seamlessly links everyday places with deep-time events. You’ll read about gold-rush mining camps and vineyard soils, but all of it is rooted in tectonics, uplift, erosion, and transformation. I’ve gotten some of my favorite stories here on California Curated from the pages of this book. It can be ponderous at times, but you’ll not regret giving it a try.
Obi Kaufman’s California Lands Trilogy is one of the most visually stunning and ambitious projects in California natural history publishing. Beginning with The Forests of California, the first of three volumes that reimagine the state not through its highways or cities but through its living systems, Kaufman invites readers to see California as a vast and interconnected organism, a place defined by its natural rhythms rather than human boundaries. Each book is filled with delicate watercolor maps and diagrams by the author himself. The result is part art book and part ecological manifesto, a celebration of the interconnectedness of California’s natural world. Kaufman’s talents as an artist are breathtaking. If he ever offered his original watercolors for sale, I’d be among the first in line to buy them. Taken together, the series forms a panoramic vision of the state’s natural environments.
That said, Kaufman’s books can be dense, filled with data, maps, and cross-references that reward slow reading more than quick browsing. If I’m honest, I tend to dip in and out of them, picking them up when I’m bored or need a break from the latest political bombshell. Every page offers something to linger over, whether it’s a river system painted like a circulatory map or a meditation on the idea of rewilding. For anyone fascinated by California’s natural systems, all Kaufman’s Field Atlases are invaluable companions endlessly worth revisiting.
My first job out of college was with the Department of the Interior in Washington, D.C., by far by the nation’s largest land management agency. A big part of that work involved traveling to sites managed by Interior across the country. I came to understand just how vast America’s public lands are and how much of that expanse, measured in millions of acres, is under the care of the Bureau of Land Management (BLM).
Josh Jackson takes readers on a road trip across California’s often overlooked public wilderness, focusing on the lands managed by the BLM, an agency once jokingly referred to as the Bureau of Livestock and Mining. He shows how these so-called “leftover lands” hold stories of geology, Indigenous presence, extraction, and conservation.
His prose and photography (he has a wonderful eye for landscapes) together invite the reader to slow down, look closely at the subtleties of desert mesas, sagebrush plains, and coastal bluffs, and reckon with what it means to protect places many people have never heard of. His use of the environmental psychology concept of “place attachment” struck a chord with me. The theory suggests that people form deep emotional and psychological bonds with natural places, connections that shape identity, memory, and a sense of belonging. As a frequent visitor to the Eastern Sierra, especially around Mammoth Lakes and Mono Lake, I was particularly drawn to Jackson’s chapter on that region. His account of the lingering impacts of the Mining Act of 1872, and how its provisions still allow for questionable practices today, driven by high gold prices, was eye-opening. I came away with new insights, which is always something I value in a book.
I should mention that I got my copy of the book directly from Josh, who lives not far from me in Southern California. We spent a few hours at a cafe in Highland Park talking about the value and beauty of public lands, and as I sat there flipping through the book, I couldn’t help but acknowledge how striking it is. Part of that comes from Heyday Books’ exceptional attention to design and production. Heyday also publishes Obi Kaufman’s work and they remain one of California’s great independent publishers. But much my appreciation for the book also comes from from Jackson himself, whose photographs are simply outstanding.
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What makes this book especially compelling is its blend of adventure and stewardship. Jackson doesn’t simply celebrate wildness; he also lays out the human and institutional connections that shape (and threaten) these public lands, from grazing rights to mining to climate-change impacts. Some readers may find the breadth of landscapes and stories a little ambitious for a first book, yet the richness of the journey and the accessibility of the writing make it a strong addition for anyone interested in California’s endless conflict over land use: what should be used for extraction and what should be preserved? While I don’t fully agree with Jackson on the extent to which certain lands should be preserved, I still found the book a wonderful exploration of that question.
Amy Tan’s The Backyard Bird Chronicles is a charming and unexpectedly personal journal of bird-watching, set in the yard of Tan’s Bay Area home. Tan is an excellent writer, as one would expect from a wildly successful novelist (The Joy Luck Club, among others). But she also brings a curiosity and wonder to the simple act of looking across one’s backyard. I loved it. Who among us in California doesn’t marvel at the sheer diversity of birds we see every day? And who hasn’t wondered about the secret lives they lead? A skilled illustrator as well as a writer, she studies the birds she observes by sketching them, using art as a way to closely connect with the natural world around her.
What begins as a peaceful retreat during the Covid catastrophe becomes an immersive odyssey of observation and drawing. Tan captures the comings and goings of more than sixty bird species, sketches their lively antics, as she reflects on how these small winged neighbors helped calm her inner world when the larger world felt unsteady.
My only quibble is that I was hoping for more scientific depth; the book is more of a meditation than a field study. Still, for anyone who loves birds, sketching, or the quiet beauty of everyday nature, it feels like a gentle invitation to slow down and truly look.
California is the most botanically diverse state in the U.S. (by a long shot), home to more than 6,500 native plant species, about a third of which exist nowhere else on Earth. Jared Farmer’s Trees in Paradise: A California History follows four key tree species in California: the redwood, eucalyptus, orange, and palm. Through these examples, Farmer reveals how Californians have reshaped the state’s landscape and its identity. It’s rich in scientific and historical detail. I have discovered several story ideas in the book for California Curated and learned a great deal about the four trees that we still see everywhere in the California landscape.
In telling the story of these four trees (remember, both the eucalyptus and the palm were largely brought here from other places), Farmer avoids easy sentimentality or harsh judgment, instead exploring how the creation of a “paradise” in California came with ecological costs and profoundly shaped the state’s identity. While the book concentrates on those four tree categories, its detailed research and insight make it a compelling read for anyone interested in the state’s environment, history, and the ways people shape and are shaped by land.
Blue whale off the California coast. (Photo: Erik Olsen)
Not So Big: How We Overstate the Length of the Blue Whale, Earth’s Largest Creature
One of the most extraordinary privileges of living in California, especially near the coast, is witnessing the annual arrival of blue whales. I’ve been at sea on several occasions when these giants surfaced nearby, and to see one in person, or even through my drone RC, is astonishing and unforgettable. I once had the rare and mind-blowing opportunity to swim with and film blue whales off the southern tip of Sri Lanka for a story I wrote and produced, an experience that will forever be seared into memory.
For decades, the blue whale has been celebrated as the largest creature ever to exist (Bigger than dinosaurs! True.), with many popular accounts claiming that these animals can reach lengths of 100 feet or more. Yet in all the videos, photographs, and encounters I’ve seen, not a single whale has come close to that. Still, article after article and documentary after documentary continues to repeat the claim that blue whales “reach 100 feet or more.” Nearly every whale-watching company in California repeats the claim, echoed endlessly across Instagram and TikTok.
But is it true? Most blue whales I’ve seen off the coast of California are half that size or maybe 2/3. It felt misleading to say so otherwise. And so I did a lot of digging: reading, reaching out to experts, poring over historical records, and the fact is that no single blue whale has ever been scientifically measured at 100 feet. Close, as you will soon read, but not 100 feet or more. Especially not off the coast of California.
This discrepancy not only distorts our understanding of these magnificent creatures, but also highlights the broader issue of how media can shape and sometimes mislead public perception of scientific facts.
Blue whale tail fluke in Sri Lanka. (Photo: Erik Olsen)
In other words: the perception that blue whales commonly reach lengths of 100 feet or more likely stems from a combination of historical anecdotes, estimation errors, and a tendency to highlight extreme examples.
All that said, the blue whale (Balaenoptera musculus) is a truly magnificent creature. Hunted nearly to extinction in the 17th to 19th centuries, the blue whale has staged a hopeful recovery in the last five decades, since commercial whaling was outlawed by the international community in 1966 (although some Soviet whale hunting continued into the early 1970s). And California, in particular, has been blessed with the annual appearance of the largest population of blue whales in the world, called the Eastern North Pacific population, consisting of some 2,000 animals. That population makes an annual migration from the warm waters of Baja California to Alaska and back every year. This is the group I’ve seen off Newport Beach.
These numbers are painfully, tragically small compared to what existed before commercial whaling began. Prior to that, it was estimated that there were some 400,000 blue whales on earth. 360,000 were killed in the Antarctic alone. (IMO: this stands as one of the most shameful acts in human history).
The International Union for Conservation of Nature estimates that there are probably between 5,000 to 15,000 blue whales worldwide today, divided among some five separate populations or groups, including the Eastern North Pacific population. Many now swim so close to shore that an entire whale-watching industry has flourished along the California coast, especially in the south, with many former fishing boats converted into whale-watching vessels..
But back to size, or, more specifically, length: there are two credible references in scientific papers of blue whales that are near 100 feet. The first is a measurement dating back to 1937. This was at an Antarctic whaling station where the animal was said to measure 98 feet. But even that figure is shrouded in some suspicion. First of all, 1937 was a long time ago, and while the size of a foot or meter has not changed, a lot of record-keeping during that time is suspect, as whales were not measured using standard zoological measurement techniques (see below). The 98-foot specimen was recorded by Lieut. Quentin R. Walsh of the US Coast Guard, who was acting as a whaling inspector of the factory ship Ulysses. Sadly, there is scant detail available about this measurement and it remains suspect in the scientific community.
The second is from a book and a 1973 paper by the late biologist Dale W. Rice, who references a single female in Antarctica whose “authenticated” measurement was also 98 feet. The measurement was conducted by the late Japanese biologist Masaharu Nishiwaki. Nishiwaki and Rice were friends, and while both are deceased, a record of their correspondence exists in a collection of Rice’s papers held by Sally Mizroch, co-trustee of the Dale W. Rice Research Library in Seattle. Reached by email, Dr. Mizroch said that Nishiwaki, who died in 1984, was a very well-respected scientist and that the figure he cited should be treated as reliable.
According to Mizroch, who has reviewed many of the Antarctic whaling records from the whaling era, whales were often measured in pieces after they were cut up, which greatly introduces the possibility for error. That is likely not the case with the 98-foot measurement, which took place in 1947 at a whaling station in Antarctica where Nishiwaki was stationed as a scientific observer.
Blue whale (NOAA)
Proper scientific measurements, the so-called “standard method”, are taken by using a straight line from the tip of the snout to the notch in the tail flukes. This technique was likely not used until well into the 20th century, said Mizroch. In fact, it wasn’t until the 1940s that the use of a metal tape measure became commonplace. According to Dan Bortolotti, author of Wild Blue: A Natural History of the World’s Largest Animal, many of the larger whales in the whaling records — especially those said to be over 100 feet — were probably measured incorrectly or even deliberately exaggerated because bonus money was paid to whalers based on the size of the animal caught.
So, according to the best records we have, the largest blue whale ever properly measured was 98 feet long. Granted, 98 feet is close to 100 feet, but it’s not 100 feet, and it’s certainly not over 100 feet, as so many otherwise reputable references state.
So, setting aside the fact that so many sources say the blue whale has reached 100 feet or more, and that there is no scientific evidence proving this, a key question to ask is how large can whales become?
Blue whale from the National Oceanic and Atmospheric Administration
Most baleen whales are so-called lunge feeders. They open their mouths wide and lunge at prey like krill or copepods, drawing in hundreds of pounds of food at a time. Lunge-feeding baleen whales, it turns out, are wonderfully efficient feeders. The larger they become, the larger their gulps are, and the more food they draw in. But they also migrate vast distances, and oftentimes have to dive deep to find prey, both of which consume a large amount of energy.
A 2019 scientific paper in Science described how a team of researchers used an ocean-going Fitbit-like tag to track whales’ foraging patterns, hoping to measure the animals’ energetic efficiency, or the total amount of energy gained from foraging, relative to the energy expended in finding and consuming prey. The team concluded that there are likely ecological limits to how large a whale can become and that maximum size in filter feeders “is likely constrained by prey availability across space and time.” That is especially the case in today’s era, when overfishing and illegal fishing, including krill harvesting in Antarctica, have reduced the amount of prey available even in regions that used to be very prolific.
Whale fall off the California Coast (Ocean Exploration Trust)
John Calambokidis, a Senior Research Biologist and co-founder of Cascadia Research, a non-profit research organization formed in 1979 based in Olympia, Washington, has studied blue whales up and down the West Coast for decades. He told California Curated that the persistent use of the 100-foot figure can be misleading, especially when the number is used as a reference to blue whales off the coast of California.
The sizes among different blue whale groups differ significantly depending on their location around the globe. Antarctic whales tend to be much bigger, largely due to the amount of available food in cold Southern waters. The blue whales we see off the coast of California, Oregon, Washington and Alaska, are part of a different group from those in Antarctica. They differ both morphologically and genetically, and they consume different types and quantities of food. North Pacific blue whales, our whales, tend to be smaller and likely have always been so. Calambokidis believes that the chances any blue whales off the West Coast of the US ever reaching anything close to 100 feet is “almost non-existent”.
I emailed Regina Asmutis-Silvia, Executive Director North America of Whale and Dolphin Conservation, to ask about this discrepancy among so many seemingly authoritative outlets. She wrote: “While it appears biologically possible for blue whales to reach or exceed lengths of 100’, the current (and limited) photogrammetry data suggest that the larger blue whales which have been more recently sampled are under 80 feet.” Photogrammetry is the process of using several photos of an object — like a blue whale — to extract a three-dimensional measurement from two-dimensional data. It is widely used in biology, as well as engineering, architecture, and many other disciplines. Photogrammetry measurements are now often acquired by drones and have proven to be a more accurate means of measuring whale size at sea.
Antarctic whaling station.
Here’s a key point: In the early part of the 20th century and before, whales were measured by whalers for the purpose of whaling, not measured by scientists for the purpose of science. Again, none of this is to say that blue whales aren’t gargantuan animals. They are massive and magnificent, but if we are striving for precision, it is not accurate to declare, as so many articles and other media do, that blue whales reach lengths of 100 feet or more. Or to insinuate that this size is in any way common. This is not to say it’s impossible that whales grew to or above 100 feet, it’s that, according to the scientific records, none ever has.
A relevant point from Dr. Asmutis-Silvia about the early days of Antarctic whaling: “Given that whales are long-lived and we don’t know at what age each species reaches its maximum length, it is possible that we took some very big, very old whales before we started to measure what we were taking.”
In an email exchange with Jeremy Goldbogen, the scientist at Stanford who authored the study in Science above, he says that measurements with drones off California “have been as high as 26 meters” or 85 feet.
So, why does nearly every citation online and elsewhere regularly cite the 100-foot number? It probably has to do with our love of superlatives and round numbers. We have a deep visceral NEED to be able to say that such and such animal is the biggest or the heaviest or the smallest or whatever. And, when it comes down to it, 100 feet is a nice round number that rolls easily off the tongue or typing fingers.
All said, blue whales remain incredible and incredibly large animals, and deserve our appreciation and protection. Their impressive rebound over the last half-century is to be widely celebrated, but let’s not, in the spirit of scientific inquiry, overstate their magnificence. They are magnificent enough.
The story of corals in the modern age on this planet is one of near-total despair. I’ve done several stories on corals and have spent many hours diving reefs around the world, from the Mesoamerican Reef in Belize to the unbelievably robust and dazzling reefs in Indonesia. There are still some incredible places where corals survive, but they are becoming fewer and farther between. I don’t want to get too deep into all the statistics, but suffice it to say: scientists estimate that we have already lost about half of the world’s corals since the 1950s, and that number could rise to as much as 90 percent by 2050 if current rates of bleaching and die-offs continue.
What’s crazy is that we still don’t completely understand corals, or exactly why they are dying. We know that corals are symbionts with microscopic algae called zooxanthellae (pronounced zo-zan-THEL-ee). The corals provide cover, a place to live, and nutrients for the algae. In return, the algae provide sugars and oxygen through photosynthesis, fueling coral growth and reef-building. But when the planet warms, or when waters become too acidic, the relationship often collapses. The algae either die or flee the coral. Without that steady food source—what one scientist I interviewed for this story called “a candy store”—corals turn ghostly white in a process known as bleaching. If stressful conditions persist, they starve and die.
The Great Barrier Reef, once Earth’s largest living structure, has suffered five mass bleaching events since 1998, and vast stretches have become little more than graveyards of coral skeletons. The scale of this ecological disaster is almost unimaginable. And so scientists around the world are in a race to figure out what’s happening and how to at least try to slow down the bleaching events sweeping through nearly every major reef system.
An image of Montipora coral polyps taken with the BUMP. Each polyp has a mouth and a set of tentacles and the red dots are individual microalgae residing inside the coral tissue. (Photo: Or Ben-Zvi)
One place where scientists are making small strides is at the Jaffe Lab, which I visited with my colleague Tod Mesirow and where researchers like Dr. Jaffe and Dr. Or Ben-Zvi have developed a new kind of underwater microscope that allows them to get close enough to corals to actually see the algae in action.
This is no small feat. Zooxanthellae are only about 5–10 microns across, about one-tenth the width of a human hair, and invisible to the naked eye. With the new microscope and camera system, though, they can be seen in astonishing detail. The lab has captured unprecedented behavior, including corals fighting with each other for space, fusing together, and even responding to invading algae.
When I first reported on this imaging system years ago, it was still in its early stages. At the time, it was known as the BUM for Benthic Underwater Microscope. Since then, the Scripps team has added a powerful new capability: a pulsing blue light that lets them measure photosynthesis in real time. They call it pulse amplitude modulated light or PAM, and so now the system is known as the BUMP.
A field deployment of the BUMP in the Red Sea, where local corals were imaged and measured. (Photo: Or Ben-Zvi)
Here’s how it works: blue excitation light stimulates the algae’s chlorophyll, which then re-emits some of that energy as red fluorescence. By tracking how much of this red fluorescence is produced, researchers can calculate indices of photochemical efficiency, essentially how well the algae are converting light into energy for photosynthesis. This doesn’t give a direct count of sugars or photons consumed, but it does provide a reliable window into the health and productivity of the algae, and by extension, the coral itself.
What’s crucial is that all of this imaging takes place in situ—right in the ocean, on living reefs—rather than in the artificial setting of an aquarium or laboratory.
New tools are essential if we’re going to solve many of our biggest problems, and it’s at places like Scripps in California where scientists are hard at work creating instruments that help us see the world in entirely new ways. “There’s so much to learn about the ocean and its ecosystems, and my own key to understanding them is really the development of new instrumentation,” says Jaffe.
Dr. Ben-Zvi gave us a demonstration of how the system works in an aquarium holding several species of corals, including Stylophora, a common collector’s coral. She showed us the remarkable capabilities of the camera-microscope, which illuminated and brought into crisp focus the tiny coral polyps along with their algal partners. On the screen we watched them in real time, tentacles waving as they absorbed the flashes of light from the BUMP, appearing, almost, as if they were dancing happily.
What this new tool allows scientists to do is determine whether corals may be under stress from factors like warming seas, pollution, or disease. Ideally, these warning signs are detected before the corals expel their zooxanthellae and bleach. Researchers are also learning far more about the everyday behavior of corals: something rarely studied in situ, directly in the ocean.
That in-their-native-environment aspect of the work is crucial, because corals often behave very differently in aquariums than they do on wild reefs. That’s where this microscope promises to be a powerful tool: offering insights into how corals really live, fight, and respond to stress.
Of course, what we do once we document a reef under stress is another matter. Dr. Ben-Zvi suggests there may be possibilities for remediation, though she admits it’s difficult to know exactly what those are. Perhaps reducing pollution, limiting fishing, or cutting ship traffic in vulnerable areas could help. But given that we seem unable—or unwilling—to stop the warming of the seas, these measures can feel like stopgaps rather than solutions. Still, knowledge is the foundation for any action, and this new tool is a breakthrough for coral imaging. If deployed widely, it could generate an invaluable dataset for researchers around the globe. The scientists behind it even hope to build multiple systems, perhaps commercializing them, to vastly expand the reach of this kind of monitoring.
But even Jaffe concedes it may already be too late: “Could a world exist without corals? Yeah, I think so,” he said. “It would be sad, but it’s going that way.”
All the same, the images the tool produces are breathtaking, and at the very least, they might jolt people into realizing that this is a crisis worth trying to solve. If we can’t, then future generations will be left only with these hauntingly beautiful images to remember the diverse and gorgeous animals that once flourished along the edges of the sea.
A healthy coral reef in Indonesia (Photo: Erik Olsen)
Is that valuable? Yes, but not nearly as valuable as saving the living reefs themselves. Dr. Jaffe told us,
“I’m on a mission to help people feel empathy toward the creatures of the sea. At the same time, we need to learn just how beautiful they are. For me, the combination of beauty and science has been at the heart of my life’s work.”
His words capture the spirit of this research. The underwater microscope isn’t just a scientific instrument. It’s a lens into a hidden world, one that may inspire people to care enough to act before it’s gone. Too bad the clock is ticking so fast.
Flasks of Asparagopsis taxiformis growing at Scripps Institution of Oceanography. Researchers are studying this red seaweed for its potential to slash methane emissions from cattle when added in small amounts to their feed. (Photo: Erik Olsen)
Inside a long, brightly lit basement lab at the Scripps Institution of Oceanography at UC San Diego, a large aquarium filled with live corals sits against the wall, the vibrant shapes and colors of the coral standing out against the otherwise plain white surroundings. Nearby, in a side alcove, dozens of glass flasks bubble with aerated water, each holding tiny crimson clusters of seaweed swirling in suspension, resembling miniature lava lamps. These fragile red fragments, born in California and raised under tightly controlled conditions, are part of a global effort to harness seaweed to fight climate change.
Cattle and other ruminant livestock are among the largest contributors to methane emissions worldwide, releasing vast amounts of the gas through digestion and eructation. Burps, not farts. The distinction is not especially important, but it matters because critics of climate science often mock the idea of “cow farts” driving climate change. In reality, the methane comes primarily from cow burps, not flatulence.
But I digress.
Cattle at Harris Ranch in California’s Central Valley, one of the largest beef producers in the United States. Livestock operations like this are a major source of methane emissions, a greenhouse gas more than 80 times as potent as carbon dioxide over a 20-year period. (Photo: Erik Olsen)
Globally, livestock are responsible for roughly 14 percent of all human-induced greenhouse gases, with methane from cattle making up a significant portion of that total. The beef and dairy industries alone involve more than a billion head of cattle, producing meat and milk that fuel economies but also generating methane on a scale that rivals emissions from major industrial sectors. Because methane is so potent, trapping more than 80 times as much heat as carbon dioxide over a 20-year period, the livestock industry’s footprint has become a central focus for climate scientists searching for solutions.
Enter Jennifer Smith and her colleagues at the Smith Lab at Scripps in beautiful La Jolla, California. Their team is tackling urgent environmental challenges, from understanding coral die-offs to developing strategies that reduce greenhouse gas emissions, among them, the cultivation of seaweed to curb methane from cattle.
The seaweed species is Asparagopsis taxiformis. Native to tropical and warm temperate seas and found off the coast of California, in fact right here off the coast in San Diego, it produces natural compounds such as bromoform that interfere with the microbes in a cow’s stomach that generate methane gas, significantly reducing the production of methane and, of course, it’s exhalation by the animals we eat. It turns out the seaweed, when added to animal feed can be very effective:
Asparagopsis taxiformis, commonly known as red sea plume, a tropical red algae being studied for its ability to cut methane emissions from cattle. (Photo: Wikipedia)
“You need to feed the cows only less than 1% of their diet with this red algae and it can reduce up to 99% of their methane emissions,” said Dr. Or Ben Zvi, an Israeli postdoctoral researcher at Scripps who studies both corals and seaweeds.
Trials in Australia, California, and other regions have shown just how potent this seaweed can be. As Dr. Ben Zvi indicated, even at tiny doses, fractions of a percent of a cow’s feed, other studies have shown that it can reduce methane by 30 to 90 percent, depending on conditions and preparation. Such results suggest enormous potential, but only if enough of the seaweed can be produced consistently and sustainably.
“At the moment it is quite labor intensive,” says Ben Zvi. “We’re developing workflows to create a more streamlined and cost-effective industry.”
Which explains to bubbling flasks around me now.
Scripps Institution of Oceanography at UC San Diego (Photo: Erik Olsen)
The Smith lab here at Scripps studies every stage of the process, from identifying which strains of Asparagopsis thrive locally to testing how temperature, light, and carbon dioxide affect growth and bromoform content. Dr. Ben Zvi is focused on the life cycle and photosynthesis of the species, refining culture techniques that could make large-scale cultivation possible. At Scripps, environmental physiology experiments show that local strains grow best at 22 to 26 °C and respond well to elevated CO₂, information that could guide commercial farming in Southern California.
The challenges, however, are considerable. Wild harvesting cannot meet demand, and cultivating seaweed at scale requires reliable methods, stable yields, and affordable costs. Bromoform content varies widely depending on strain and growing conditions, so consistency remains an issue. Some trials have noted side effects such as reduced feed intake or excess mineral uptake, and long-term safety must be established since we’re talking about animals that we breed and raise to eat.
“It’s still a very young area, and we’re working on the legislation of it,” says Ben Zvi. “We need to make it legal to feed to a cow that eventually we either drink their milk or eat their meat. We need for it to be safe for human consumption.”
Dr. Or Ben Zvi (Photo: Erik Olsen)
And, of course, large-scale aquaculture raises ecological questions, from nutrient demands and pollution to the fate of volatile compounds like bromoform.
To overcome these obstacles, collaborations are underway. UC San Diego and UC Davis have launched a pilot project under the UC Carbon Neutrality Initiative to test production methods and carbon benefits. In 2024, CH4 Global, a U.S.-based company with operations in New Zealand and Australia that develops seaweed feed supplements to cut livestock methane, partnered with Scripps to design cultivation systems that are efficient, inexpensive, and scalable. Within the Smith Lab, researchers are continuing to probe the biology of Asparagopsis, mapping its genetics, fine-tuning its culture, and testing ways to maximize both growth and methane-suppressing compounds.
At a time when university-based science faces immense pressures, the Smith Lab at Scripps provides a glimpse of research that is making a real impact. The coral tanks against the wall belong to another project at the lab, and we have another story coming soon about the research that readers will find very interesting, but the bubbling flasks in the alcove reveal how breakthroughs often start with small details. In this case, the discovery that a chemical in a widely available seaweed could have such a dramatic, and apparently harmless, effect on the methane that animals make in their guts. These modest but powerful steps are shaping solutions to global challenges, and California, with its wealth of scientific talent and institutions, remains at the forefront. It is one of many other stories we want to share, from inside the labs to the wide open spaces of the state’s natural landscapes.
It’s time for California to put people back in the deep. A human-occupied submersible belongs in California waters, and we’ve waited long enough.
For decades, the state had a strong human-occupied submersible presence, from Navy test craft in San Diego to long-serving civilian science HOVs like the Delta. Those vehicles have been retired or relocated, leaving the West Coast without a single home-based, active human-occupied research submersible (I am not counting OceanGate’s Titan sub for numerous reasons, like the fact it was based in Seattle, but foremost is it was not “classed,” nor was it created for scientific use). Restoring that capability would not only honor California’s legacy of ocean exploration but also put the state back at the forefront of direct human observation in the deep sea. The time has come.
Side note: I’ve had the rare privilege of diving beneath the waves in a submersible three times in three different subs, including one descent to more than 2,000 feet with scientists from the Woods Hole Oceanographic Institution. Without exaggeration, it stands among the greatest experiences of my life.
The United States once had a small fleet of working research HOVs. Today it has essentially one deep-diving scientific HOV in regular service: Alvin, operated by Woods Hole Oceanographic Institution (WHOI) for the National Deep Submergence Facility. Alvin is magnificent, now upgraded to reach 6,500 meters, but it is based on the Atlantic (in Massachusetts) and scheduled years in advance at immense cost.
The human-occupied submersible Alvin surfaces during the 2004 “Mountains in the Sea” Expedition, returning from a dive to explore deep seamount habitats teeming with corals, sponges, and other rarely seen marine life. (Photo: NOAA, Public Domain)
It helps to remember how we got here. The Navy placed Alvin in service in 1964, a Cold War investment that later became a pillar of basic research, investigating hydrothermal vents, shipwrecks and underwater volcanoes, among many, many other accomplishments. Over six decades of safe operations, Alvin has logged thousands of dives and undergone multiple retrofits, each expanding its depth range. Now rated to 6,500 meters, it can reach 98 percent of the ocean floor. WHOI’s partnership model with the Navy and universities shows exactly how public investment and science can reinforce each other. But Alvin is based on the East Coast: all that capability, history, and expertise is thousands of miles away. California needs its own Alvin. Or something even better…and perhaps cheaper. Though by cheaper I do not mean less safe.
For a time, California actually had multiple HOVs. The Navy fielded sister craft to Alvin, including Turtle and Sea Cliff. Both Turtle and Sea Cliff spent their careers with Submarine Development Group ONE in San Diego. Turtle was retired in the late 1990s, and Sea Cliff, launched in 1968 and later upgraded for greater depths, also left service by the end of that decade, ending the Navy’s home-ported HOV presence on the West Coast.
On the Atlantic side, Harbor Branch’s two Johnson Sea Link HOVs supported science and search-and-recovery work for decades before the program ended in 2011 due to funding constraints and shifting research priorities. I’ve interviewed renowned marine biologist Edith Widder several times, and she often speaks about how pivotal her dives in the Johnson Sea Link submersibles were to her career studying animal bioluminescence.
“Submersibles are essential for exploring the planet’s largest and least understood habitat, ” Widder told me. “A human-occupied, untethered submersible offers an unmatched window into ocean life, far surpassing what remotely operated vehicles can provide. ROVs, with their noisy thrusters and blazing lights, often scare away marine animals, and even the most advanced cameras still can’t match the sensitivity of the fully dark-adapted human eye for observing bioluminescence.”
In the central Pacific, the University of Hawaiʻi’s HURL operated Pisces IV and V for much of the 2000s and 2010s, then suspended operations amid funding and ship transitions. Through attrition and budget choices, the working U.S. fleet shrank from a handful to essentially one deep-diving research HOV today.
Manned submersibles are costly to build and operate, and they demand specialized crews, maintenance, and support ships or platforms. It’s easy to list reasons why California shouldn’t invest in a new generation of human-occupied subs. But that mindset has kept us out of the deep for far too long. It’s time to turn the conversation around and recognize why having one here would be a transformative asset for science, education, and exploration.
The Seacliff and Turtle submersibles (Photo: U.S. Naval History and Heritage Command photo. Public Domain)
California’s own human-occupied sub legacy is short, but notable. In addition to the Navy submersibles noted above, the Delta submersible, a compact, ABS-class HOV rated to about 1,200 feet, operated from Ventura and later Moss Landing, supporting dozens of fishery and habitat studies from the Southern California Bight to central California. Built by Delta Oceanographics in Torrance, Delta dives in the mid-1990s produced baseline data that still underpin rockfish management, MPA assessments, and predictive habitat maps. The sub’s ability to place scientists directly on the seafloor allowed for nuanced observations of species behavior, habitat complexity, and human impacts that remote tools often miss. Many of these datasets remain among the most detailed visual records of California’s deeper reef ecosystems.
The Monterey Bay Aquarium Research Institute (MBARI) operates a world-class research fleet with a robust remotely operated vehicle (ROV) program, but no human-occupied vehicle—a strategic decision the institute made years ago in favor of robotics over direct human dives. (Photo: Erik Olsen)
In the late 1990s, the program shifted north to Moss Landing, where it was operated in partnership with the Monterey Bay Aquarium Research Institute (MBARI) and other institutions. At the time, MBARI was still in the early years of exploring human-occupied vehicles, like Bruce Robison’s experience piloting the Deep Rover HOV in Monterey Canyon in 1985. To many at MBARI, human occupancy in submersibles began to seem more like a luxury than a necessity. If the goal was to maximize scientific output and engineering innovation, remotely operated vehicles offered longer bottom times, greater payload capacity, and fewer safety constraints. That realization drove MBARI to invest heavily in ROV technology, setting the stage for a long-term move away from human-occupied systems.
Which leads us to the present moment: California’s spectacular coast faces mounting environmental threats, just as public interest in ocean science wanes. And yet, we have no human-occupied research submersible, no way for scientists or the public to directly experience the deep ocean that shapes our state’s future.
The Delta submersible, once a workhorse of California’s deep-sea research with over 5,800 dives, operated from Ventura and later Moss Landing between the 1980s and 2000s. Sold in 2011 in a non-functional state, it remains out of service—symbolizing the end of the state’s home-ported human-occupied submersible era.
Look, robots are incredible. MBARI’s ROVs and AUVs set global standards, and they should continue to be funded and expanded. But if you talk to veteran deep-sea biologists and geologists, they will tell you that being inside the environment changes the science.
Dr. Adam Soule, chief scientist for Deep Submergence at the Woods Hole Oceanographic Institution (WHOI) agrees, “Having a human presence in the deep sea is irreplaceable. The ability for humans to quickly and efficiently process the inherently 3D world around them allows for really efficient operations and excellent sampling potential. Besides, there is no better experience for inspiring young scientists and for ensuring that any scientist can get the most out of unmanned systems than immersing themselves in the environment.”
Some of our most prominent voices are also speaking out about the need to explore the ocean. I recently produced an hour-long episode of the PBS science program NOVA and one episode was about the new generation of submersibles being built right now by companies like Florida-based Triton Submarines. I had the privilege of talking to filmmaker and ocean explorer James Cameron, who was adamant that human participation in ocean exploration is critical to sustaining public interest and political will.
“The more you understand the ocean, the more you love the ocean, the more you’re fascinated by it, and the more you’ll fight to protect it,” Cameron told me.
The author with James Cameron in front of his submersible the Deepsea Challenger. (Erik Olsen)
Human eyes and brains pick up weak bioluminescence out of the corner of vision, pivot to follow a squid that just appeared at the edge of a light cone, or decide in the moment to pause and watch a behavior a diving team has never seen before. NOAA’s own materials explain the basic value of HOVs this way: you put scientists directly into the natural deep-ocean environment, which can improve environmental evaluation and sensory surveillance. Presence is a measurement instrument.
California is exactly where that presence would pay off. Think about Davidson Seamount, an underwater mountain larger than many national parks, added to the Monterey Bay National Marine Sanctuary because of its ancient coral gardens and extraordinary biodiversity. We know this place mostly through ROVs, and we should keep using them, but a California HOV could carry sanctuary scientists, MBARI biologists, and students from Hopkins Marine Station or Scripps into those coral forests to make fine-scale observations, sample with delicacy, and come home with stories that move the public. Put a student in that viewport and you create a career. Put a donor there and you create a program.
A time-lapse camera designed by MBARI engineers allowed researchers to observe activity at the Octopus Garden between research expeditions. (Photo: MBARI)
Cold seeps and methane ecology are another natural fit. Off Southern California and along the borderlands there are active methane seep fields with complex microbial and animal communities. Recent work near seeps has even turned up newly described sea spiders associated with methane-oxidizing bacteria, a striking reminder that the deep Pacific still surprises us. An HOV complements ROV sampling by letting observers linger, follow odor plumes by sight and instrument, and make rapid, in-situ decisions about fragile communities that are easy to miss on video. That kind of fine-grained exploration connects directly to California’s climate priorities, since methane processes in the ocean intersect with carbon budgets.
There are practical use cases all over the coast. A California HOV could support geohazard work on active faults and slope failures that threaten seafloor cables and coastal infrastructure. It could conduct pre- and post-event surveys at oil-and-gas seep sites in the Santa Barbara Channel to ground-truth airborne methane measurements. It could document deep-water MPA effectiveness where visual census by divers is impossible. It could make repeated visits to whale falls, oxygen minimum zone interfaces, or sponge grounds to study change across seasons.
An autonomous underwater craft used to map DDT barrels on the seafloor off California. (Photo: Scripps Institution of Oceanography at U.C. San Diego)
It could also play a crucial role in high-profile discoveries like the recent ROV surveys that revealed thousands of corroding barrels linked to mid-20th-century DDT dumping off Southern California. Those missions produced stark imagery of the problem, but a human-occupied dive would have allowed scientists to make on-the-spot decisions about barrel sampling, trace-chemical measurements, and sediment core collection, as well as to inspect surrounding habitats for contamination impacts in real time. The immediacy of human observation could help shape quicker, more targeted responses to environmental threats of this scale.
And it’s not just the seafloor that matters. Some of the most biologically important parts of the ocean lie well above the bottom. The ocean’s twilight zone, roughly 200 to 1,000 meters deep, is a vast, dimly lit layer that contains one of the planet’s largest reservoirs of life by biomass. (My dive with WHOI was done to study the ocean’s twilight zone). Every day, trillions of organisms participate in the planet’s largest migration, the diel vertical migration, moving up toward the surface at night to feed and returning to depth by day. This zone drives global carbon cycling, supports commercial fish stocks, and is home to remarkable gelatinous animals, squid, and deepwater fishes that are rarely seen in situ.
Launching the Triton 3300/3 (Photo: Erik Olsen)
The Triton 3300/3’s 1,000-meter depth rating (I’ve been in one twice) puts the entire twilight zone within reach, enabling direct observation of these daily movements, predator-prey interactions, and delicate species that often disintegrate into goo in nets. Human presence here allows scientists to make real-time decisions to follow unusual aggregations, sample with precision, and record high-quality imagery that captures how this midwater world works, something uncrewed systems alone rarely match.
It could even serve as a classroom at depth for carefully designed outreach dives, giving educators footage and first-person accounts that no livestream can quite match. Each of these missions is stronger with people on site, conferring, pointing, deciding, and noticing.
While Monterey Bay would be a natural fit because of MBARI, Hopkins, and the sanctuary’s deepwater treasures, Southern California could be just as compelling. Catalina Island, with its proximity to submarine canyons, coral gardens, and cold seeps of the Southern California Bight, offers rich science targets and the existing facilities of USC’s Wrigley Marine Science Center. Los Angeles or Long Beach would add the advantage of major port infrastructure and a vast urban audience, making it easier to combine high-impact research with public tours, donor events, and media outreach. And San Diego with its deep naval history, active maritime industry, Scripps Institution of Oceanography, and proximity to both U.S. and Mexican waters, could serve as a southern hub for exploration and rapid response to discoveries or environmental events. These regions could even share the vehicle seasonally: Monterey in summer for sanctuary work, Catalina/LA or San Diego in winter for Southern California Bight missions, spreading both benefits and funding responsibility.
The author in front of the Triton 3300/3 in the Bahamas (Photo: Erik Olsen)
For budgeting, a proven benchmark is the Triton 3300/3, a three-person, 1,000-meter (3,300-foot) human-occupied vehicle used widely in science and filming. New units are quoted in the four to five million dollar range, with recent builds coming in around $4–4.75 million depending on specifications. Beyond the vehicle, launch and recovery systems such as a 25–30-ton A-frame or LARS and the deck integration required for a suitable support ship can run into the high six to low seven figures. Modern acrylic-sphere subs like the Triton are designed for predictable, minimized scheduled maintenance, but budgets still need to account for annual surveys, battery service, insurance, and ongoing crew training. Taken together, a California-based HOV program could be launched for an initial capital investment of roughly $6–7 million, with operating budgets scaled to the number of missions each year. So, not cheap. But doable for someone of means and purpose and curiosity. See below.
Who would benefit if California restored this capability? Everyone who already works here. MBARI operates a world-class fleet of ROVs and AUVs but has no resident HOV. Scripps Institution of Oceanography, Hopkins Marine Station, and USC’s Wrigley Marine Science Center train generations of ocean scientists who rarely get the option to do HOV work without flying across the country and waiting for a slot. NOAA and the sanctuaries need efficient ways to inspect resources and respond to events. A west-coast human-occupied research submersible based in Monterey Bay, Catalina, Los Angeles, or San Diego would plug into ship time on vessels already here, coordinate with ROV teams for hybrid dives, and cut mobilization costs for Pacific missions.
A new Triton 660 AVA submersible slips into the turquoise waters of the Bahamas, beginning its first voyage. Built for dives to 660 feet (200 meters), it offers passengers a front-row seat to reefs, shipwrecks, and marine life far beyond normal scuba limits, making it an ideal draw for high-end tourism. (Photo: Erik Olsen)
What would it take? A benefactor and a compact partnership. California has the donors (hello, curious billionaires!), companies, and public-private institutions to do this right. A philanthropic lead gift could underwrite acquisition of a proven, classed HOV and its support systems, while MBARI, Scripps, or USC could provide engineering, pilots, and safety culture within the UNOLS standards that govern HOV operations. No OceanGates. Alvin’s long record shows the model. Add a state match for workforce and student access, and a sanctuary partnership to guarantee annual science priorities, and you have a durable program that serves research, stewardship, and public engagement.
Skeptics will say that robots already do the job. They do a lot of it. They do not do all of it. If the U.S. is content to have only one deep research HOV based on the opposite coast, we will forego the unique perspectives and serendipity that only people bring, and we will keep telling California students to wait their turn or watch the ROV feed from their laptops or phones. California can do better. We did, for years, when the Delta sub spent long seasons quietly counting fish and mapping habitats off Ventura and the Channel Islands. Then that capability faded. If we rebuild it here, we restore a missing rung on the ladder from tidepools to trenches, and we align the state’s science, climate, and education missions with a tool that is both a laboratory and a conversion experience.
The author at more than 2000 feet beneath the surface of the ocean. (Photo: Erik Olsen)
Start with a compact, 1,000-meter-class HOV that can work daily in most of California’s shelf and slope habitats. Pair it with our ROVs for tandem missions and cinematography of the sub and its occupants in action. Commit a share of dives to student and educator participation, recorded and repackaged for museums and broadcast. Reserve another share for rapid-response science at seeps, landslides, unusual biological events, or contamination crises like the DDT dumpsite. Build a donor program around named expeditions to Davidson Seamount, Catalina’s coral gardens, and the Channel Islands. Then, if the community wants to go deeper, plan toward a second vehicle or an upgrade path. The science is waiting. The coast is ready. And the case is clear. California should restore its human-occupied submersible fleet.
