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  • Writer's pictureThe San Juan Daily Star

Obsessed with the ocean, Susan Casey takes the plunge

Susan Casey in Gardiner, N.Y., July 19, 2023. Casey has long been enchanted by the deep ocean — for her book “The Underworld,” she finally got to visit that unforgiving landscape herself.

By Alexandra Alter

Some writers go to the ends of the earth in pursuit of a great story. Susan Casey went to the bottom of the ocean.

While researching her new book, “The Underworld,” about the otherworldly inhabitants of the deep ocean and the explorers and scientists who are surveying these uncharted depths, Casey ventured down in deep sea submersibles, visiting eerie, alien landscapes that no humans had ever seen.

The deep sea makes up more than 90% of earth’s biosphere, yet stunningly little is known about it. That’s starting to change, with new technology, such as smart drones that are mapping the ocean floor, and with expeditions in cutting-edge submersibles by private explorers such as director James Cameron and private equity investor Victor Vescovo, who set a new world record when he reached the deepest point of the Mariana Trench, some 36,000 feet below the surface.

Casey became fascinated by the deep ocean while visiting the Farallon Islands, an archipelago some 30 miles from San Francisco Bay, where she was researching great white sharks for her 2005 book “The Devil’s Teeth.” “It started to occur to me that there was this parallel universe right beneath the surface,” she said. “What’s down there? What’s going on? What don’t we see?”

Her deep sea adventures were exhilarating, and occasionally harrowing.

On a dive, Casey and Vescovo plunged more than 5,000 meters (16,400 feet) to explore the ecosystem at the base of an underwater volcano in Hawaii, where they saw carpets of neon orange microbes and navigated a maze of lava formations. During a trip to the bottom in the Bahamas, Casey panicked briefly when the submersible’s pilot noticed water around their feet, and tasted it to determine if the water was fresh, from condensation, or salty, from a leak. It was fresh, and they continued exploring, flying over dunes of snow white silt.

In a phone interview from her landlocked home in New York’s Hudson Valley, Casey spoke about the most awe-inspiring life form on the planet, how the recent tragic accident involving the OceanGate submersible could impact deep sea expeditions, and why deep sea mining poses an unfathomable threat to the planet. Below are edited excerpts from the conversation.

Q: Given how massive and important it is, why do you think we’ve paid so little attention to the deep ocean?

A: For the longest time, there was this sense of, it’s this barren, lifeless place. It’s dark. The pressures are pretty insane as you get deeper. How could anything live there?

It took a really long time for people to understand that there is life throughout the entire water column. When you hit the seafloor, there’s a whole other ecosystem that extends even below the seafloor. So, this vast, vast, vast, vast majority of our world is down there in the dark.

But as far as funding for research, that’s a very good question. I don’t understand it at all. I’m really hopeful that that will change for the better. It’s starting to dawn on people that this is the major part of our world. It’s the engine that drives the climate cycle. It basically is where 90% of the earth’s microbial life is. There is a lot that we will need to know about how the planet works as a whole in order to be able to survive this next period of intense change.

Q: You write with alarm about companies’ plans to extract minerals from the seafloor. What are the risks?

A: It would be destroying an ecosystem before we even know what we have lost. Scientists are racing to research the area that will be affected first, which is called the Clarion-Clipperton Zone, the area of the Pacific between Mexico and Hawaii, a vast area that’s like 2 million square miles.

Every time they go out there and sample a tiny area, they come back with specimens, and 92% of them are new species. In the microbial realm, they are finding hundreds of thousands of creatures like microorganisms that are not only new species, they’re like new branches on the tree of life.

These are microbes that have figured out how to survive over hundreds of millions of years in an incredibly harsh environment. Those compounds will lend themselves to us learning a lot about resilience. That is probably where the answers lie to really intractable problems like antibiotic resistant drugs. We have just scratched the surface on this.

Q: While you were researching this book, there were big leaps in exploration. Do you think that progress will continue, especially in the wake of the Titan disaster?

A: I think it absolutely will continue.

We’ve just gone through this collective trauma of watching the Titan submersible implode, but it’s really important that people understand that that submersible has nothing in common whatsoever with the machines that I’m writing about and the machines that I dived in.

Manned submersibles have the most impeccable safety record of any mode of transportation, in the world’s riskiest environment. So, that shows how seriously that is taken. OceanGate did not take that seriously.

Q: Did you hear about OceanGate while researching the book?

A: I was aware of OceanGate. I had a friend who was the chief pilot of the University of Hawaii’s deep sea submersibles and ran the Hawaii Undersea Research Lab. He told me about a lot of the things that have come out. So, I was aware of it and had steered very clear of it. You’ll notice there’s no mention of OceanGate in my book, although all other organizations that deal with the deep ocean are in my book.

Q: It seems like many people in the field raised alarms about the risks the company was taking.

A: Everybody tried their hardest. There’s a limit to what you can do. Technically, there’s no law against what he was doing. I hope that changes.

Q: Part of the arc of this book has you going from understanding the vastness of the deep ocean intellectually, to being physically immersed in it. What was it like to be in that environment?

A: Unlike space, you’re surrounded by life. The deepest dive I did, we fell for maybe 2 1/2 hours. You just get a sense of we’re just in one little, tiny spot, and you get a more visceral sense of the immensity of it.

Q: You use an evocative phrase to describe life at the very bottom of the ocean — intraterrestrial life. What’s happening under the seafloor?

A: The seafloor and the ocean crust and even deeper, it’s not solid. It’s got fissures and little, tiny, fractured aquifers. So, there’s microbial life that extends far beneath the seabed.

Archaea are the oldest. They found these archaea existing in places that they really didn’t think any life should be able to exist, at temperatures far higher than it should be able to survive, in poisonous chemical environments where it didn’t seem like anything should be able to survive. There’s nothing that I could read about microbes that would shock me. They’re just extraordinary. They run this planet.

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