Deep-Sea Tourism or Deep-Sea Science?

Today, as in eras past, a lot of wealthy men fancy themselves explorers. The tragic—but, by most accounts, foreseeable and preventable—loss of five passengers and crew on a sub dive down to the wreckage of the Titanic in June got us thinking about what genuine undersea exploration looks like. On our latest episode of the Smithsonian magazine podcast “There’s More to That,” I speak with Tony Perrottet, who profiled the late OceanGate CEO Stockton Rush for Smithsonian magazine in 2019, about his experience reporting that story, and about our ancient fascination with exploring hostile environments. I next speak with Susan Casey, who has written four best-selling books about the ocean and its creatures, the newest of which is The Underworld: Journeys to the Depths of the Ocean. (You can read an excerpt from The Underworld here.) Susan tells us why understanding the ocean is key to humanity’s survival, and how while serious research and shipwreck tourism may have some overlap, they remain two very different things.

A transcript of the episode is below.

Chris Klimek, host: One day, Tony Perrottet opened his newspaper and read about a submersible going missing in the Atlantic Ocean near the wreck of the Titanic.

Tony Perrottet, Smithsonian magazine contributor: It was kind of a surreal experience reading about it, because to have this personal connection was kind of unexpected and a little haunting, really.

Klimek: In 2019, Tony spent time with OceanGate founder Stockton Rush, while on assignment for Smithsonian magazinewhile on assignment for Smithsonian magazine. He even got a chance to take a ride in a submersible called the Cyclops. The Cyclops was a sister vehicle to the Titan, the ship that imploded, killing all five passengers, including Rush.

Perrottet: At the beginning, we thought that everyone’s sort of stuck down there slowly running out of air, and I could, of course, have visualized this probably more than most since I’ve been on the Cyclops. But the whole thing was very strange, and it brought up a lot of emotions.

Klimek: Tony recalled his brief trip to the bottom of Washington State’s Puget Sound one stormy day four years ago.

Perrottet: You’ve got the oculus, the eye there, and it sort of slides off at an angle in, and you see the water rising up, and it was very murky. I think they call it the “milkshake.” There was some filtered light, and then you go down there and there’s the silence.

Klimek: After about 20 minutes, it was time to resurface.

Perrottet: So we just sat there, and then you come up, and then when you see the water line and it’s slightly distorted, it is kind of a magical sort of feeling, sort of defying nature. And so that was very exciting. Nevertheless, it ain’t natural.

Klimek: That alluring yet unsettling feeling is not the only thing Tony took away from this experience, which is why we gave him a call. This news story got us thinking about the nature of underwater exploration and of exploration itself. Who gets to call themselves an explorer now? What does the idea of traveling to the depths of the ocean spark in our imaginations? And who’s actually making discoveries that can help make life better on land?

From Smithsonian magazine and PRX Productions, this is “There’s More to That,” a podcast where journalists often travel to remote locations to bring you the context behind the headlines. On today’s show, we take a deep dive into the ocean with two people who have a lot to say about it. I’m Chris Klimek—here we go.

Tony Perrottet met OceanGate CEO Stockton Rush at a hotel in Seattle during a rare snowstorm. A reminder that just because you haven’t prepared for something doesn’t mean it can’t happen.

Perrottet: And they only got a couple of inches of snow, but in Seattle that’s so rare. The whole city was paralyzed, so it took him ages to get out of his four-wheel drive to meet me. It was all very dramatic, and we were there in this strange little cocoon really, and watching the snow come down. It was very silent and sort of eerie, as if we were in a submarine at the bottom of the ocean, in a weird way.

Klimek: Rush would frequently draw on science fiction as he described his underwater ambitions.

Perrottet: All his references were “Star Trek” references. He wanted to be Captain Kirk on the Enterprise. He wanted to be the one exploring and discovering stuff.

Klimek: He even framed the risks of deep sea travel in “Star Trek” language.

Perrottet: He once compared being over-worried about safety, was being worried that the Klingons were going to attack. It’s a remote possibility.

Klimek: Rush did build his business around people’s fascination with the deep sea and exploration, the romanticism of figures like Captain Nemo or even Indiana Jones.

Perrottet: The whole Titanic thing, it was a marketing ploy in a way. He was trying to get people interested in deep ocean and he’s like, “How do you get people interested?” Most people, if you talk about what’s in the ocean, most people think of whales, sharks or the Titanic, and people love shipwrecks. But then if you ask people to name a shipwreck, he said, “It’s like Titanic, Titanic and Titanic.” It gets people’s imaginations going.

Klimek: Down to the price of a ticket aboard the submersible, Rush was trying to tap into this sense of adventure that the Titanic seemed to inspire in those who could afford it.

Perrottet: It was like a great PR stroke. He decided: What are we going to charge to take people down to the Titanic? And he got the price of the first-class ticket as it was in 1912, and he put it into the Department of Labor’s inflation thing online, and he got massive publicity because of this. It ended up going up to $250,000, but he was a great entrepreneur. He was able to sense what people would get excited about.

Klimek: Tony explained that there’s been a morbid fascination surrounding the wreck of the Titanic ever since people started diving there in the mid-’80s.

Perrottet: Particularly after, in the early years, when people were going down in the 1990s, the first submersibles going down, and people were taking things, and they took a strip of the Titanic and all these odds and ends that are now on display in the Luxor Casino in Las Vegas. There’s an extreme voyeurism there.

Klimek: It turns out the human appetite for morbid tourism goes back to ancient times.

Perrottet: The ancient Romans and the Greeks had the same sort of thing. They would go as tourists to ancient Egypt, and they were fascinated by the Cult of the Dead, and yet they also were worried that they were crossing a line.

Klimek: Some believed there were consequences to this.

Perrottet: There’d be these tragedies, like the Emperor Hadrian would … his lover drowns, and it’s as if the Gods are going to seek some revenge on us for being too morbidly obsessed with death.

Klimek: This is an idea that persisted throughout human history.

Perrottet: The Victorians were very ambivalent about archeological research in Egypt, shipping back mummies, basically grave robbing and putting them on display, and these stories that are spiritually wrong or that you’re going to bring some curse down upon you.

Klimek: Moving into the 20th century, Tony cited the story of an English earl named Lord Carnarvon. He was the man who funded the search and excavation of King Tutankhamun’s tomb in Egypt. In 1922, less than five months after first setting foot inside of it, he died of a mysterious, seemingly cursed, mosquito bite. Several other archeologists and self-styled explorers who visited the tomb or examined remains taken from it also died shortly after. Newspapers reported the deaths as a so-called Curse of the Pharaohs. Since then, dozens of movies have been made about curses falling upon those who would dare violate an ancient sacred space.

Do you think the persistence of those stories supports this idea, like maybe we should leave these sites of tragedy be and not go sticking our noses in?

Perrottet: Yeah, I think it taps into these moral, spiritual dreads, and maybe with the Titanic it’s a bit like that. Why? Why do we need to dwell on this pretty dismal sort of thing? Why do we have to find the shoes, the jewelry of these people who died in this great tragedy? What’s wrong with us? Many people do regard the Titanic site as a mass grave in a way, which it was. Sort of like this obsession with it can sometimes seem like it’s tempting fate or something, or it brings up a lot of weird superstition in a way.

Klimek: And yet this romantic idea of what an explorer is has stuck around. Tony says that Stockton Rush came from a long line of people with grand notions of groundbreaking discovery.

Perrottet: He reminded me of one of these 19th-century characters, very privileged upbringing, American aristocracy really, and his [ancestors] had signed the Declaration of Independence, and so he reminded me of the English aristocrats who would give up everything to go the Amazon and then die and enduring all sorts of bizarre challenges and discomforts and losing their fortunes to do these things. And yet it seemed to him he didn’t have any choice. He felt compelled to do this.

Klimek: But of course it was a choice. It’s a choice that we see so many of these eccentric billionaires make, whether they go to the bottom of the ocean or into space, and what they may not realize is that the nature of being an explorer has changed a lot.

Perrottet: There’s certainly a longing to discover things and to do something original. I guess it’s the frontier thing as well, somewhat tainted now that we realize that this discovery thing is often quite ambiguous. The discovery of Machu Picchu, for example, turns out a local villager knew all about it and just pointed him the way. Things like that, and the whole idea of the frontier is obviously Native Americans are like, “What the hell?” And this idea of discovery and exploration that runs through travel in general, first world people going off into third world countries and discovering things and the newness and reaching the last untouched highland tribe in New Guinea, it’s no longer quite as romantic as it was in the 1920s and ’30s as we realized the devastating consequences of all this.

And yet the idea of climbing that last mountain or finding that lost tributary, it’s like the Explorers Club in New York has this huge problem. It used to have … you become a member if you find some geographical thing that no one’s ever found before, but they’ve run out of them. But to be the first person to see something, it is a very romantic idea, and it just captures the imagination in a way that seems to be embedded in our culture in a certain way. Weirdly, I suppose in a sense, the underwater thing is actually a slightly purer thing, because it’s like, you’re not necessarily disenfranchising people.

Klimek: OceanGate claimed it was engaging in scientific discovery, but it mostly boiled down to a tourism venture for the ultrarich. We were curious about what actual underwater discovery looks like today at depths even deeper than the wreck of the Titanic. Luckily, we knew who to call. Susan Casey is the author of a new book called The Underworld: Journeys to the Depths of the Ocean. You can read an excerpt from The Underworld at Smithsonianmag.com.

While writing it, she traveled to ocean research sites around the globe to find out how human survival is linked to the deep ocean and how submersibles are being used for vital research. We began by talking about her own fascination with the ocean.

So basically your beat is the ocean, most of the planet. Tell us how this became your beat.

Susan Casey, author, The Underworld: Journeys to the Depths of the Ocean: Well, it was always a major interest. I can’t even remember when that started. My first conscious memory is of just being fascinated by water and always wanting to be in the water and always wanting to know what was under the water, and it just has never, ever left me. I always think of myself as a proxy for curious people who may not want to go out themselves and hang out with great white sharks or get on the top of a 70-foot wave or go 70,000 feet down into a volcano, but are interested to know what that would be like. So that’s what animates me.

And I always want to go with scientists, because they’re the ones who can really put into context all the fascinating things that are happening in the environment. It’s cool to see it, but it’s even cooler when you find out what’s going on and what they’re learning from it, which is just like every time they go down there, they come back with new species, they come back with new questions, they come back with new knowledge. To me, it’s just endlessly fascinating, and I like to spread my fascination through stories.

Klimek: Yeah, I was struck as I’m just learning for this segment about the names of the various layers of the deep ocean that seem to have poetic significance. Can you walk us through those layers, please?

Casey: Yes. Well, so there are different ways to delineate the deep ocean. The deep ocean typically is considered to be the water below 600 feet. So the top layer of the deep ocean beneath the sunlight layer, which ends at 600 feet, is called the twilight zone or the Mesopelagic. Below the twilight zone is the midnight zone, which is from 3,300 to 10,000 feet. And then below that is the abyssal zone, which is also known as the abyss, and it is from 10,000 to 20,000 feet, and that’s where a lot of the seafloor is, at those abyssal depths.

But there’s a lower depth in the subduction zones where tectonic plates come together and create these deep V-shaped trenches, and that’s known as the hadal zone, named after Hades, god of the underworld. Those are very deep. They go from 20,000 to 36,000 feet, but they’re very long, narrow trenches like the Mariana Trench, and so they don’t account for a lot of the footprint of the deep ocean, but they account for 45 percent of its depth. So they’re really significant in terms of just the sheer depth of them, but they only take up, I think it’s about 2 percent of the footprint of the seafloor.

Klimek: So even the term “ocean floor” is a little misleading, because it makes you picture something that is of roughly uniform depth, but that’s really not what it’s like. It’s pocketed with these deep, deep trenches.

Casey: I think there was something like 27 hadal trenches, but that number is surprisingly fluid. I remember trying to pin it down when I was writing in my book, and it’s like as they learn more about the seafloor, they find out more about these hadal environments, and a lot of them haven’t been explored very much, and the seafloor has only been mapped at high resolution across about 25 percent of it. So every time we get more high-resolution data about the seafloor, it’s like putting a lens on the Hubble Telescope.

Klimek: So as I understand it, the belief initially was that the surface of the earth must be expanding if the ocean floor is constantly changing, but it’s not. Why is that?

Casey: Because of subduction, the whole theory of how continental plates move was, from what I understand, a knock-down, drag-out science argument that went on for a long time until it was finally settled. They are moving and they’re drifting, they’re moving. Now, they’ve discovered the mid-ocean ridge where the plates are pulling apart, and they saw that when the plates pull apart, magma comes up from below and creates new seafloor and squeezes mountains on the sides. So if that’s happening all the time, the earth must be expanding.

But what is so cool is that on the opposite side of the plate, the plate is subducting. So as the plates meet and butt heads with each other, one of them is driven downward, it is exposed to tremendous heat and pressure and melts and goes back into the mantle. So at the same time, new seafloor is being built, old seafloor is being consumed in perfect equilibrium, which is really extraordinary.

I remember one scientist saying to me that the largest geological feature on earth is the mid-ocean ridge, which is where tectonic plates are pulling apart. It’s a 40,000-mile, basically, area. If you imagine earth like a baseball, the mid-ocean ridge is like the seams on a baseball, and in those areas the plates are pulling apart and new seafloor is coming up, as well as all kinds of microbial life, volcanic vents happen there. So there’s a lot of action along the mid-ocean ridge, and it’s very big.

So what the scientist said to me was every day along the mid-ocean ridge, there are explosions going off, likely at supersonic speed, changing the chemistry of the seawater around them, bringing up microbial life from deeper within the seafloor and the mantle. And we don’t understand how that affects the whole, and there’s just a lot of very talented people out there trying to find out. And one thing that’s exciting is that there are advances in technologies that are making it possible to do things that weren’t possible in the past, but it’s still … We have a long way to go before we can say we really understand how the ocean works.

Klimek: I think this is so little understood what you’re saying about just how volatile even the composition of the ocean at those lower depths is. We imagine, certainly, the composition to be this static thing, and it’s not. You’re saying there’s constantly new elements being introduced to the water as a result of tectonic activity. Is that broadly correct?

Casey: Yeah, absolutely. When I first started this, like you said, tended to think of the seafloor as pretty solid, but when you get below the seafloor, it was explained to me it’s like a bowl of marbles. So there are actually microbial creatures living deep beneath the seafloor in the cracks and the fissures. Really interesting new discoveries in terms of what they call the “deep biosphere.”

Klimek: To really underscore the idea that this isn’t just some vague quest for knowledge in the broad sense, you wrote about how microbes on the ocean floor led to the development of ways to test for Covid-19.

Casey: Yeah, I don’t know the actual details of the chemistry behind it, but it was a microbe from a volcanic vent was used for the enzyme that was used to develop the test for Covid-19.

Klimek: It turns out that this microbe contained an enzyme that could remain stable even at very high temperatures. Scientists leveraged this characteristic to develop the PCR test in the 1980s. Now it’s used to test for Covid and other kinds of viruses, and that’s not all.

Casey: There’s another microbe that was found in deep-sea sediments in the Atlantic that has been found to kill cancer cells, and it is in final clinical trials. They’ve studied it for glioblastoma, which is the cancer that killed John McCain, and it was found in deep-sea sediments in the Bahamas at 3,642 feet, and it is incredibly effective. It’s being developed by Scripps, and it was discovered by scientists at the Scripps Institution of Oceanography, and the scientists that discovered it said basically it just killed cancer cells, completely killed them.

Klimek: Susan included this discovery in her book. While she was writing, she also spent time with Paul-Henri Nargeolet, one of the passengers who died aboard OceanGate’s Titan submersible. Susan called him by the nickname P.H. I asked her about when she first learned the submersible had gone missing.

Casey: I just stopped in my tracks. I was walking in New York City and I just thought, “Oh no.” Because everybody who knew anything about that submersible worried that the problem with it was that it potentially could implode, and it did. So I texted another person who’s in my book who knows a lot about this manufacturer of submersibles, and said, “Please tell me P.H. wasn’t on that.” And he said he was on it, and P.H. was a real icon of the deep and one of the most experienced deep submergence people in the world. Nobody could figure out what he was doing on that sub, because it was, to put it mildly, an incredibly unorthodox sub that had skirted all of the usual safety regulations, submersible classification processes that all the other subs go through. And because they all go through it, there hasn’t been a fatality in a manned submersible for 50 years, and there’s never been an implosion.

But OceanGate did not do this. This is not somebody’s opinion. This is the laws of physics, and the materials that he used for the sub were not the right materials for that environment, and the shape of the sub was not the correct shape for that environment. It’s just really tragic, and it didn’t have to happen.

Klimek: And I guess why Nargeolet would even want to go is a question, given this is not a person who would be seduced by the novelty value of going down to the wreckage of the Titanic.

Casey: Yeah, I can tell you right now there’s a lot of confused people, and a lot of people tried to talk him out of it, but he was very connected to the wreck of the Titanic. He did a lot of the retrieval of conservation of objects that were going to disintegrate. Thirty dives, 35 dives, and he was a historian of it as well, and he knew the stories of all the people who were on board. Really, if I had to guess it was that he just could not resist the chance to go back down there, and this was the only sub that was going down there.

Klimek: Can you please tell us about your experience with Mr. Nargeolet, the time you spent with him as you were doing the reporting for your book?

Casey: We sailed together in the Pacific. He was there to oversee everything that was happening and just make sure that everything was safe. I was a little intimidated, but he is an incredibly humble man. He was 73 when I met him in 2019. I described him in my book as a dashing character, because that’s how he came across to me. P.H. cleared all kinds of mines from the seabed, from Hitler’s troops, booby-trapped bombs in the English Channel, and was just a badass. He was a captain of the French Navy. He was a saturation diver. He had stories, P.H. had stories, and he was just incredibly kind. I remember just sitting and talking to him. He really just loved the ocean. So that was really super fun to talk to him about it, because he had seen so much.

Klimek: That’s a terrible loss. In your opinion, was what OceanGate was doing, was that scientific exploration?

Casey: No, because they had no sampling capability on their sub. In order to do scientific exploration and have a science-class sub, you need all kinds of mechanisms to secure samples, to be able to identify them, to keep them at pressure as you’re coming. It’s complicated. I read somewhere that they were talking about using the skids of the submersible to take sediment samples, and I phoned up a friend of mine who’s a microbiologist at the University of Georgia and told her that, and she laughed. It was just like, it’s of no use. I think what they did do was take 4K video, but you’re seeing video at one point in time, and I’ve been on scientific expeditions and I’ve seen the amount of gear they have, and no, OceanGate was not doing science. Maybe a little bit of archeology, maybe a little bit of videography, and maybe that’s of some use, but without a manipulator arm, you’re pretty limited.

And I think what he was doing was what I would call “science-washing,” where he was making it sound as if there was a whole lot of important science going on. I’m not saying there’s no science to be done at the Titanic, but there have been a lot of dives to the Titanic over the years. A lot more than many other places in the ocean. And I don’t know, aside from microbiologists who have studied the way that shipwreck is being consumed by microbes, I’m sure any deep-sea scientist, you offer them a chance to get back into the deep sea, they’re going to take it. But that is not a hotbed of science, the wreck of the Titanic.

Klimek: Some news reports, including one in the Wall Street Journal, have mentioned a sampling device built for the Titan by a firm called eDNAtec. Neither eDNAtec nor OceanGate responded to our requests for comment. We asked Susan to clarify whether this device was the one she and her microbiologist friend were talking about. She confirmed by email that it was, writing, “OceanGate was taking water samples for eDNA, but they had only one bottle, which is a bit of a joke. They had no zero sediment sampling capability, and wiping sediment off the skids is not serious to say the least.”

Do you think there’s any value to ferrying tourists down to the wreck site? I know Rush would make the argument that, “Well, I have to fund the science with a little tourism.” Are you at all sympathetic to that argument?

Casey: Oh yeah, I totally am. If he had done this correctly, it probably wouldn’t have made financial sense. But the idea of using well-heeled adventurers who want to see the Titanic to fund real scientific research with real submersibles that function safely and reliably in the deep-sea environment, I’m all for that mission. There’s a big gap between idea and execution here. The problem is, I think, in order to make a deep-sea … the reason there aren’t that many that take passengers is because it’s very expensive. And he tried to change the business model by making it a different material, making it so he could have five people in the passenger hull, and all of those things may be necessary for the business plan, but the deep ocean doesn’t care about your business plan.

Klimek: That means safety is paramount. We’re talking details as minute as facial hair. That’s right: Susan gave us a long list of precautions submersible crew members normally take.

Casey: There are a lot of rules. If you’re a man, you have to shave your beard to make sure that there’s no oxygen leakage should there be an oxygen event. Nobody’s messing around with the element, that’s for sure.

Klimek: That’s not something that would’ve occurred to me, certainly. So you mean when for oxygen leakage, are you actually talking about if you have to put a rebreather on so that it doesn’t interfere with the seal?

What are some of the discoveries that submersibles have brought to us?

Casey: One of my favorites is, now I don’t know if the listeners will be familiar with it, and a lot of people have seen pictures of the subs that have an acrylic hull, plexiglass hull, like James Cameron has one. You see them in films a lot, because they’re great for filming, because a really deep-sea submersible doesn’t have the option of having an acrylic hull. They’ll have a titanium hull or a steel hull with smaller view ports, but they’ve now got an acrylic hull that can go to 2,000 meters. So there’s a lot you can see in film and you get a 340 degree panoramic view. These subs have been really popular for documentaries and things like that. And Ray Dalio, who started OceanX with his son Mark Dalio, they have one of these subs and they loaned it to a group of scientists who were looking for the giant squid off the coast of Japan.

And so footage of a live giant squid was taken from one of these submersibles, and it was just incredible. The marine biologist, Edie Widder, had created a flashing lure that she thought would draw in a giant squid, which of course were incredibly elusive. And I believe this might’ve been as recent as 2012 or 2015. It was recent. And she put that lure out there and not only did the giant squid come, it stayed for a long time. It looked like it was made of metal. It was so beautiful. So they’re really good, those subs, for being able to see the environment and understand the environment.

Klimek: How are the oceans and our climate connected? As the ocean absorbs heat, absorbs carbon, what are the consequences of that?

Casey: We’re going to find out—obviously it will change the chemistry. The ocean is becoming more acidic as the carbon is absorbed by the ocean, and it does take up a lot of our heat and excess carbon dioxide, and nobody exactly knows what the mechanism for that is. But part of it is this biological carbon pump that happens in the twilight zone where these trillions of little animals make the world’s largest animal migration every single night and come up closer to the surface from say, a couple thousand feet down, eat phytoplankton, sun-nourished, carbon phytoplankton, swim back down and excrete into the depths. Some of it is sequestered for years, and other bits that make it as far as the seafloor are sequestered for centuries. So there’s a lot of complicated mechanisms, including these trillions of animals doing this, the effects that heat will have on them.

It’s not going to be good for any ocean organisms. I shouldn’t say any. It will probably be good for species of jellyfish and certain other creatures that can evolve or adapt to that changing. But a cold ocean is a nutrient-rich ocean. So it’s not great news. If you look at how El Niño, even, impacts the ocean, you can get a sense of it. It’s hard on seabirds, it’s hard on marine creatures. It’s just warmer is harder. There is a lot of—how do I put it?—biological intelligence in the ocean. There is a microbial realm called the “rare biosphere” that seems to be hanging back, waiting for conditions to change. And if they do, that particular type of microbe might flourish again. And there’s been evidence of, after volcanic eruptions, whole new regimes of microbial life will come in. So we could see drastic changes in the ocean, and none of them will be good for us, because the way things work now is how we’ve evolved to live and what we’ve come to rely on and where we’ve built our cities and where we’ve built our houses.

Klimek: The biggest concern for Susan isn’t just the building we’ve done in the past. It’s where humans may go digging in the future. She’s particularly alarmed by talk of deep-sea mining and the harvesting of resources like diamonds, cobalt, gold and zinc.

Casey: Deep-sea mining hasn’t happened on any sort of industrial scale yet, but there are a lot of parties that would like it to start happening. And if it is allowed to go forward, it has the potential to be the largest extractive industry we have ever engaged in by an order of magnitude. Each mine site, at least in the first phase of this, would be 30,000 square miles. So it’s potentially devastating to the seafloor. I don’t think we should do it. I don’t think we need to do it. And one of the main reasons I don’t think we should do it is because we don’t know what’s down there. And you hear a lot of talk about, well, we need metals for a greener future. Well, that’s not the way to get them. There are a lot of options that we could pursue before taking the last intact carbon-capturing wilderness that we have on the planet and tearing it up before we even know what lives there.

And by lives there, I mean all of that microbial life that we’ve been talking about. And there’s a lot of scientists that would like to see between 10 to 30 years of further study before this is even considered, because they’re going to be going for these manganese nodules. I think of them as trees, but they’re made of metal, but they’ve got microorganisms inside them. There are microorganisms that live under them. There are animals that live specifically in manganese nodule fields, because that’s the habitat they’ve evolved to live in, and they grow like pearls. Metals accrete from the seawater over the course of millions and millions of years, and so it’s not like it’s a sustainable resource. We take these nodules away, and they’re not coming back, and the animals that live on them are not coming back, at least on any time scale that makes any sense for humanity. So time to proceed with caution here.

Klimek: So to try to contrast with the horrific consequences of that—as you’ve described in some detail—as you were reporting your book, spending time with these scientists and oceanographers, did you witness anything exciting or hopeful that gave you any reasonable cause for optimism?

Casey: I’m always optimistic. I always say “desperately hopeful.” I think the fact that they’re out there at all is cause for optimism, and I think people are interested. I think people are quite fascinated by the ocean. When something is discovered in the ocean, people pay attention.

Klimek: Susan Casey is the author of The Underworld: Journeys to the Depths of the Ocean. Thank you so much for talking with us today, Susan. This has been a fascinating conversation.

Casey: Thank you so much.

Klimek: To read Tony’s profile of Stockton Rush, as well as an exclusive excerpt from Susan’s new book, The Underworld, wherein she takes you along on a deep-sea dive to an underwater volcano, go to Smithsonianmag.com. We also have a link in our show notes. We like to close each episode with an extra pocket-sized bit of information you can use if you find yourself in a conversational lull at your next social gathering. This episode’s dinner party fact is about how a certain sea creature takes its meals.

Carlyn Kranking: Hi, I’m Carlyn Kranking. I’m Smithsonian magazine’s assistant digital editor for science and innovation. And my dinner party fact is that seahorses don’t have stomachs. So a group of scientists in Australia recently released about 380 endangered white seahorses in Sydney Harbor. They had raised the animals in captivity, and they said that they had to feed them basically constantly, because seahorses don’t have stomachs.

So I looked it up, and it’s really true. Seahorses don’t have stomachs, and they actually do not have teeth either. They just eat by slurping their prey through their snouts. And the super tiny sea creatures that they eat just start breaking down as soon as they enter a sea horse’s body. It’s actually the animals’ intestines that do the digesting, and this is a really inefficient way of eating. They don’t get much energy from it, so that’s why they have to eat so much and so constantly.

So next time you’re at a dinner party, thinking about food, maybe thinking about stomachs, you can share this fact with your friends to impress them and maybe disturb them just a little bit.

Klimek: “There’s More to That “is a production of Smithsonian magazine and PRX Productions. From the magazine, our team is me, Debra Rosenberg and Brian Wolly. From PRX, our team is Jessica Miller, Genevieve Sponsler, Adriana Rozas Rivera, Terence Bernardo and Edwin Ochoa. The executive producer of PRX Productions is Jocelyn Gonzales. Our episode artwork is by Emily Lankiewicz. Our music is from APM Music. I’m Chris Klimek. Thanks for listening.