Poured Over: Susan Casey on The Underworld

August 3, 2023

“My overarching goal is to enchant people the way I am enchanted.”

Explore the deep ocean and its wonders in Susan Casey’s The Underworld. With an eclectic cast of scientists and enthusiasts along with the author’s firsthand experience diving into the unknown of the deep, this is a one of a kind look at one of the most important features of our planet. Casey joins us to talk about the fascinating geography and animal life she’s seen, the importance of connecting with nature, the threats that face the ocean and more with guest host, Jenna Seery.

This episode of Poured Over was hosted by Jenna Seery and mixed by Harry Liang.      

Featured Books (Episode):
The Underworld by Susan Casey
The Devil’s Teeth by Susan Casey
The Wave by Susan Casey

Full Episode Transcript

Jenna Seery

I’m Jenna Seery, a bookseller and the associate producer of Poured Over and today I am here with Susan Casey. If you’ve ever had a fleeting interest in the ocean, or any of the things that happen below the waves, you’ll probably know of her books, Voices in the Ocean, the Wave, Devil’s Teeth, and now an incredible new addition to that group, The Underworld. I was truly taken on an adventure when I read this book. Susan, thank you so much for joining us today.

Susan Casey

My pleasure.

I think obviously, starting out the ocean is something that, for so many people is this huge daunting thing in our lives that many people never really encounter firsthand. I mean, I grew up in a pretty landlocked place, I never had much exposure to the ocean, I think you had a similar experience growing up, you talk about in your book, and I think it is such a great source of curiosity for so many people, because it is this huge, vast, almost an understandable thing. So how did you start your journey and love for the ocean?

I have been asked that question many times. And I’ve often searched, you know, just to try to determine if there was a moment. And the only thing that I can say is I’ve always had the draw to explore the ocean. And in particular, its water itself, that has always really fascinated me and the ocean is, you know, it’s the largest, most wild expression of that. So when I reported the Devil’s Teeth, and started spending time out in the Pacific, in the Farallon Islands, it really started to hit home to me that it was this parallel universe. And it’s so vast, I mean, if you think of the Earth as a, as a biosphere, the living space of everything on earth 98 — almost 99% of that is ocean. And it was always intriguing to me too, that okay, we can see a little bit, but we can’t see very, very much. And because of that 98% 95% of is deep ocean, the waters below 600 feet. So there is this vast, vast, you know, it’s what I call the underworld, this vast world within our world. And, you know, curiosity dictates to me that I need to find out what’s down there. I mean, there’s a lot down there.

I think that was so surprising to me, in some ways, reading this book that you think of the ocean as this huge, vast thing, there’s so much. But I think a common misconception that even I found myself fighting against reading this is that there can’t be very much that deep down, you know, there can’t be very much life or things to be learned down there. And I think that obviously has completely shifted in my mindset after reading this, because it turns out, that’s where the most exciting things are happening under the water is all the way down. I mean, the volcanoes, the life forms that are so new, and so different from anything that we can sort of conceptualize on land was incredible to sort of parse and piece through as I was reading,

You know, unlike space, the ocean is a matrix of life. So it’s this enormous, almost beyond comprehension, enormous living space. And because it’s so enormous, you don’t always see like, an extreme density of life in any one place, although in some parts of the deep ocean, you definitely do. But, you know, when you come across something, it’s usually something extraordinary. And since we haven’t really explored the depths of the ocean, to the extent that we’ve explored many other places, everything, almost everything that we discover and learned on there is something brand new, which to me is really exciting, and obviously to scientists is really exciting.

I think every time you mentioned some sort of animal or plant life, I had to like stop and Google it because there were so many things I had no frame of reference for. And I was blown away by like the different jellyfish and sort of different sea life down underneath. I think you think I thought of like angler fish and other things, but that is like not even close to what is actually very deep down even to things that are less good, like life forms that have plastic just like inside of them, which obviously is a little stressful to think about, but it was so different than what I thought. And I think that hearing the scientists’ journeys to sort of uncover all of that and to try and get people to understand a little bit more than we have in the past is such a worthwhile and incredible cause.

I would agree, I just think that if you know 95% of our planet is deep ocean, it’s not like it’s the separate thing over here. It’s the engine that drives the climate. It’s where 75% of the Earth’s volcanism comes from, it’s where our oxygen comes from, it’s where the chemical balance of the Earth is maintained, it’s, it’s really important for us in a time, especially when, you know, we’re trying to understand Earth Systems, we’re trying to understand the time that we’re coming into the time of climate change. And we can’t really understand that if we don’t fully understand how the world works, and every little bit is a part of the whole. So this notion that, oh, we’ll just live up here, and we’ll pay no attention to that — the entire, most of the world, it’s just we don’t have that ability to do that anymore.

I was very struck, you know, when you said, compared to space, because we are have all this energy and focus, it seems like over the last, you know, 100 years or so to be so gung ho about exploring space, and there’s so much on our own planet that we haven’t even looked at. And I can’t, it’s such an interesting dichotomy to be like, well, this is the great frontier space. But we haven’t even finished here yet, we’ve got so much more that we have to learn about where we currently live, and we have to stop maybe focusing so much on looking up when we still need to be looking down.

Right. I mean, I did think about that a lot as I was writing, it seems to be this sort of human tendency to want to go upwards to try to expand our horizons to you know, the idea of going inwards into inner space brings up a lot of issues. I mean, there’s there are a lot of people who are scared of the notion of the deep, the idea of going inward is a journey of surrender, really, it’s a journey of instead of conquest, it’s a journey of, okay, this is this very demanding environment, we have to make sure that we have every respect for it, we have to make sure that our machines can cope with the tremendous, almost unfathomable forces that they encounter. I mean, at the very bottom of the ocean, the pounds per square inch is 16,000. So, you know, imagine like 300 747s stacked on top of you, it requires a lot, it requires like a real commitment to going in the opposite direction of what our tendencies tell us to do.

You mentioned a lot about early submersibles and sort of the pioneering journey is down to the bottom of the ocean into different depths. And I was struck by the fact that I didn’t know most of those things that it never comes up in sort of common research or like in my travels through the world you don’t know about these pioneers, and these explorers who put so much energy and effort into understanding this. And it has traveled through you have met and know, and have worked with so many current pioneers and explorers that have this sort of drive. And I guess, sometimes I think we think we’re done exploring that there’s no more to be explored. And yet there are still so many people out there who have this drive and this focus to explore these last things,

If I could have one wish for ocean, for people to fall in love with the ocean for people to become more aware of how extraordinary it is, it would be that everybody got to go down and see the deep ocean. And that may be a sort of a counterintuitive or strange thing to say. Because as the as we’re recording this, we’ve just, you know, gone through this sort of collective trauma of seeing this submersible implode above the Titanic. But I think it’s really important to distinguish that that was in that has never happened before. That is an extremely rare situation with as will be dissected over and over again, a very unique set of circumstances that were sort of born of a complete disregard of the everything we’ve learned over the years about how to do this safely. And everything that we know about what you have to be prepared to encounter in terms of pressure and just that you do not go down there lightly. But if you can go down there, it will change your entire perspective of the planet you live on. I mean, when I dived in submersibles for the book, the overwhelming emotion that I felt was all. I mean, you just see things the magnificence of it is. It’s just humbling. And also, when I was coming up on multiple occasions, just this sense of grief, like I did not want to get out, I just wanted to be down there. It has a lot of gravitas, you know, so you’re aware of that. But it’s just a different tempo, it’s a different realm. I just, you can explore it safely. It’s not widely available, but in the future, I believe it will be more widely available, you don’t have to go down to 13,000 feet or 26 or 36, you can go down to 3000, 2000 feet and still see the top layer of the deep ocean as scientists refer to it as the Twilight Zone. And it has more animal life in it than the rest of the ocean combined. It’s I call it the Manhattan of the deep, and 90% of the creatures that are down there have the ability to use bioluminescence, it’s how they communicate its how they hunt, it’s how they mate. So you go down there, and you think you’re going to be in this void of darkest and you’re in this glittering, shimmering, twinkling, like rain of fireworks. As far as the eye can see, there are these, there are animals, tiny, tiny, in some cases, a little bigger in some cases, but you just realized, like, there is a dimension of life that’s so intensely important to the functioning of the planet, and they’re beautiful. They’re just absolutely beautiful.

Reading some of the descriptions you have of your own experiences, going to these many different depths and hear the experiences of these other scientists that sort of prove why they’re all there. And in sometimes these terrible conditions, or, you know, these difficult scientific endeavors where they’re planning these huge expeditions, and because of weather or technical malfunctions, you know, the whole thing has to be scrapped at the last second, it really makes you realize how have a tightly woven thing this all is that there is it’s not done lightly. The scientists aren’t out there just doing whatever they want to be doing. They’re making choices that are very planned, and they have these incredible submersibles with just cutting-edge technology that is constantly being updated. And I’ve never wanted to explore much of the ocean, I’m a little claustrophobic. And some of the descriptions of things I definitely had moments of feeling in my chest. But I can’t imagine the joy of getting to watch and experience the things that people get to experience in the ocean through these submersibles. And through this scientific exploration.

Yeah, I mean, I think lots of documentaries have done a wonderful job of bringing the environment up to where everybody can see it. But there isn’t the full sense of it on a screen, you know, you sort of have to experience the vitality of it. And the three dimensionality of it, you’re flying through a sea of life. And the goal is not to dive, the goal is to come home. So you know, they’re very, very, very careful about this. I mean, to the point where it can seem, it can seem really like, is all this really necessary? And it absolutely is.

I think I mean, clearly you have worked with and had the privilege to dive with and to experience some of the top, you know, scientists in the field, the different people that you’ve worked with have all been very passionate and driven. And I found myself loving most of the people that you have in these books because you able to capture sort of the essence of these teams that you worked with. How did it feel to work with these people who are so in love with the ocean and so in love with what they’re doing, whether it’s from planning the different journeys or being sort of hands on the submersibles themselves being in the submersibles. I just can’t imagine the joy of getting to work with people who love something as much as you do.

Yeah, I mean, it is there is an ocean I say this in the book, there is an ocean tribe and I’m always excited when I meet other people who are part of that tribe and want to spread the sort of the wonder of that to readers. Maybe not every reader will want to go down a 70-foot wave or you know, hang out with white sharks or dive in a submersible but come along and we can do this together. So, I’m always looking for people that are passionate almost to the point of obsession about what they do and people who I think are doing really cool things. Because it does take me a long time to record a book and I would like to spend my energy bringing a really cool little story back that excites me. There, there have been on occasions of villains. There are some villains in this book. Yeah, I prefer to spend my energy with people that I think are really doing extraordinary things and take a deep dive with them into their lives and what motivates them. And with it with an amount of immersion and detail that hopefully really gives readers a sense of them. So they feel as though they’re with them as well.

I definitely felt like I was on board with you all when you were doing your different dives. And I felt the elation of when things would go well, and the disappointment of when things didn’t go as planned in the you know, the feeling of your heart and your throat when something is waiting to happen. It definitely gives something that I don’t think you can get in certain other nature documentaries, or in other I think like so many things about nature now have transitioned to visual media, that there’s so much on TV and in movies, these documentaries, which are great, because they give a visual sense of these, you know, the things that people are seeing and that you can’t imagine otherwise, but at the same time getting to be in this book and have your perspective on things. And the way you’re seeing it, I think is a completely different feeling to understanding everything that’s going on.

I mean, that’s what I love about writing books, I think is that you get an opportunity to like, pardon the pun, you really dive deep into something. And like add a lot of texture to it. I mean, as great as some of the undersea cinematography is, and it really is extraordinary. And they spend huge amounts of time trying to find very distinctive places that you may or may not encounter on a single trip down there. But it by nature of its medium, it doesn’t have the chance to really explain a lot or add context or maybe add narrative functions or add characters, you know, so, yeah, book books, I think, to me, are the medium that interests me the most, which is why spend all my time writing them. And I totally respect and adore the readers that we’ll spend the time to. It will take the time and the focus in this very distracting world that we live in to, to take a deeper look at these incredible environments and stories and people.

I know we’ve just kind of talked around this for a little bit. But you’ve written a lot about several different facets of the ocean, you’ve written about waves, you’ve written about sharks. But how did you decide that this was going to be your next full endeavor? How did you decide that this was going to be the next book?

I had wanted to write about the deep ocean almost immediately after finishing The Devil’s Teeth. Because when I was out these islands that are off the coast of San Francisco, the Farallon Islands are just an incredibly wild place. And there are all these different ocean currents that collide there, a lot of ships have gone down out there, like it’s this wild, wild, probably the wildest place I’ve ever been. And that is largely because it’s just the ocean is wild, wild, wild out there. So we would be in this little research boat and a great white shark would pop up. And then another great white shark would pop up because they eat on the surface, the seals that, they float. So you’re seeing these sharks. And one day, I remember seeing 40 Blue Whales just come up, you know, all around the island lunch feeding. And there was a diver down there who was telling me all these things that he saw, like an anchor that was like 10 feet tall, just saw all kinds of creatures there being Mako sharks, there were little jellies that I never even knew existed called tinafors and siphonophores. And it occurred to me like, that is so unusual, like here, you see them at the surface, they come to the surface. But if you follow them down there, what would you find like what else is going on down there that we don’t know about? And so it was in my mind, but I have to say, I couldn’t, I wasn’t in a position to write about it. At that time it this is my fourth book about the ocean. And it took everything that I’ve learned in the other three books and everything I’ve learned, in general about the ocean to be able to write this book, because it’s just a bass topic. And so how do you approach it? And I didn’t focus on one part of it, I focused on all the parts of it, and all the different sciences in it, the geology, the biology, so it was a lot it was a lot and I needed that sort of foundation to be able to approach it in a way that I could simplify it into a narrative, make sense of it and still add richness to it, I hope.

I can tell by reading this, obviously, that it took years of research and years of commitment to do I mean, you talk about things from many different points in, in your life to sort of compile into this. I can’t imagine sort of the herculean task of getting all this research, which I’m sure was no small feat in itself going through and understanding all of the pieces that you wanted to put in, and then sitting down with all of it and saying, Okay, now I need to put it into one book. And this isn’t a huge tome. This isn’t like a giant 500, 700-page book. But you managed to get everything so well, intertwined. I never felt like I was lost. I had moments where I had questions, but almost always, you’d have answered it within a couple of pages when I didn’t understand something. And I appreciated that because there are so many terms and you know, different things in this book that I’d never heard before. But I just imagined sitting down in front of all your research and having to be like, Okay, now I have to write the book.

Oh, yeah, I don’t know if you could see. But I built while I was starting the book, built a big studio and haven’t actually been able to organize it yet. But there’s just paper everywhere. It’s like an explosion at the paper factory. There’s books everywhere. It’s, I’m going to step back when I can and sort of organize it all. But yeah, it was overwhelming at times. But I’ve always felt like when it gets like that, what you have to do is just sort of step back, take a breath, and tackle it one step at a time. I’m an over reporter, that’s one of my first of all, I find it fascinating. And I’m always panning what I call tend to think of as panning for gold. You know, I’ll read a huge book on something just to find one fact. And that I think is really cool, or really funny, or something like that. So it does tend to sprawl for sure.

And the bibliography in this book is immense. There’s a lot that goes in and a lot of notes and I found myself being like, well, I have to go through and look at those two and get more information. I’m the kind of person where once I get into a book, I can get very, like tunnel vision and be like, this is all I want to talk about. And if you aren’t ready to talk about it, well, you’re gonna just have to buckle up because all I want to talk about is the ocean right now. And thankfully, people have been pretty receptive on that in comparison to some of the other things.

Yeah, yeah, well, then I’ve done my job. I mean, my overarching goal is to enchant people, the way I am enchanted. You know, I remember when I first started thinking, okay, maybe I’m gonna write, I’m ready to write this, now. There was a discovery made in the Atlantic in the middle of the Atlantic. And it was a place called the lost city, which is on the cover of the book. And when I read about that, I was just like, you have got to be kidding me. I mean, it was, it’s a hydrothermal vent field, but it is unlike any other volcanic hydrothermal vent field that anybody has ever seen. And these vents have been known about since 1977, which is pretty recent. But this one was completely unique, because it wasn’t volcanic. And it was made of these towering crystalline, white structures, like they look like Gothic church steeples. And some of them are 200 feet tall. And the scientists that found it. Were just absolutely astonished. No, no, nothing like it has been found since it’s almost a dead center in the Atlantic. And as they started studying it, they realized that its chemistry was so unusual, and so different than other volcanic vents that it was most likely this type of chemistry and formation that had been the site of where life originated, they had been feeling that volcanic vents had the potential but there’s, you know, this is a scientific argument that may never be resolved completely. But this was awfully close to perfect for this. And so as they were they were in the submersible called the Alvin, which is the US Navy’s submersible, research submersible, they only had one dive. And when they went down there, they were so astonished by its beauty and the structures in it, that they named it lost city after the lost city of Atlantis. And so when I saw pictures of it, I was just mesmerized, like, to the point where I couldn’t think about anything else. I read everything I could. And when I first began work on this book, the very first person that I called was the scientist, Deb, Deb Kelly, from the University of Washington, who was on the team that discovered it and had written the papers about it afterward. And if that is down there, what else is down there? It was just like a thread that I just kept following.

I think enchantment is such a great word to use because I always think like, for me when I think about conservation, and I think about connecting people with the world that that that’s how we start conservation. I think so many people feel disconnected from the planet. They don’t have some interest that are the passion that sort of drives them forward. And they just feel like yep, this is just the thing we live on. And it’s here. And it doesn’t really have that much to do with me. But you can’t read a book like this and not feel connected to the ocean, you can’t imagine these things and these life forms and everything that’s down there the wonder and not feel connected. I can’t imagine, you know, the things I’ve changed perspective on or now just have a wider view of through reading and trying to do my own research now, after finishing, that I never knew so much of this, and how do you not feel passionate about maintaining it and saving certain things that are there.

100%. I mean, that that is my goal is this notion that we’re somehow separate from nature, or the ocean is something over there, it has nothing to do with us. That’s a mindset that will pursue at our peril. And although I don’t know how to stop the disconnection, this is my attempt to remind people that there is a real intelligence to nature, you can look at it on a screen, you can watch it, you can do anything, but it’s not the same as encountering it. And understanding that you are part of it, we are separate from anything, that’s an overarching goal that I have is to remind people of how wondrous it is and how much of a part of it we are, and how important it is that we understand that and revel in it, you know.

And there’s so much in understanding how we fit into it and sort of the things we’ve already done. I mean, you talk in this book about deep sea mining, you talk in this book about sort of the fight for who owns the ocean floor, and all these things that when we stopped to think about it, these are all decisions that are being made that really have an effect on everybody. And most people don’t even know that those decisions are even an option that those things are even there.

Deep sea mining is a really tough topic. There’s a lot of things that go on in the ocean that really upset me. I mean, plastic, as you mentioned, there are now many, many creatures, the very bottom of the ocean that are actual plastic organic hybrids, which means that they’ve got, you know, by the time the plastic gets down there, it’s nanoparticles, its micro particles, it’s embedded into their organs to the point where they’re not fully organic. They’re hybrids, plastic organic hybrids. And when I learned about that, I asked the scientists who discovered it, the first creature they found was a little crustacean, called an amphipod, and they started sampling this, it was at the bottom of the Mariana Trench, and they couldn’t find a single specimen that didn’t have this. So they named it Eurystheus Plasticus. This is the first of its kind, there are no non plastic Eurystheus. And I asked the scientists who discovered it, Alan Jameson, like do you think there are other animals down there like that? And he said, all of them. So there’s that, then there’s industrial fishing, which is just insane. I mean, bottom trawling, I can’t, it’s illegal in many parts of the world, but it’s still legal and others, and it’s done illegally as well. In Santa, it just complete insanity to destroy these seamount environments that are home to like just these huge concentration of biodiversity. We don’t know what these animals are, they have found chemical compounds and biological compounds that they found one that just kills glioblastoma cells dead in the patch of seafloor sediment. That’s the cancer, the brain cancer that killed John McCain. I mean, there’s this endless apothecary down there, it’s where we will get new antibiotics so that we aren’t stuck with the insane problem of antibiotic resistant strains of bacteria and things like that. So just to trash it before we even know it is, it’s so self-destructive doesn’t make any sense. But deep sea mining is, is that problem on many orders of magnitude greater scale, it has not happened yet, in any sort of industrial scale way, but it is imminent. And most people, as you pointed out, aren’t aware of it. So the level of destruction that it will do to the ocean, the biodiversity of the planet. It’s completely obvious that it’s going to be major. But it is completely unknown, the actual effects so it’s this, this incredible amount of risk that we’re taking for reasons that are extremely specious. The notion is that there are these manganese nodules on the bottom that have cobalt and nickel and we need this for a greener future. like listen, if we are willing to reach down for miles through the ocean and rip up the seafloor and pull out the microbial life that’s been there since the Mesozoic era that we don’t even know what it is and it goes extensive a mile beneath the seafloor even, I think it’s a it’s a wisdom test that as a species, we will have failed. So I am extremely freaked out and extremely motivated to talk about this. Because I do think when people find out about it, they’re just horrified. And it is really unclear how we can stop it because it’s being conducted under the auspices of the International Seabed Authority. It’s a complicated political thing. But even making people aware of it, and as a society saying, this is really unacceptable. Like, we don’t even need these metals, carbon, they’re not using cobalt and nickel anymore, mostly they’re trying to move away from it. By the time we have done this, it’s really unclear what the benefit would be. And it will accrue to a very, very small group people, it’s about money. Absolutely.

And like you said, it is like this, the human paradox of we say we want to do this thing to improve something. But in fact, we’re causing a problem immeasurably worse, and it feels very overwhelming and daunting, like you said to read about because it is such a huge, layered issue. But I mean, for myself, I’d heard the phrase deep sea mining, I think that’s a phrase that gets bandied about a little bit as like a threat that’s out there. But to really go through and sort of understand the grand threat is very different. And I’m too hopeful that just having people even learn that it is something looming, will be any sort of, you know, bolstering to the cause of making sure that it doesn’t happen.

Yeah, I mean, I was hopeful that my contribution in this book would be to take the very complex elements of it, which are political there, there’s a lot of complexity in here. And, and really simplified into a narrative that people could understand in one chapter to get it across very succinctly. But without having to go way into the weeds, and allowing people to, because that chapter comes later in the book, allowing people have the opportunity to understand what’s at stake in an emotional way, in the previous chapters of the book before you understand that it’s in jeopardy, so not to sprawl with it all over the book, but to keep it in one place, and really kind of hopefully put it in an impactful place. I do think that when people find out about it, they’re really astonished that it might happen. And lots of companies have already started to say they won’t use deep sea metals, and there’s a hope that we can give them the kind of scarlet letter that say blood diamonds have, like conflict minerals like these are obtained in the most destructive of destructive ways, for no particular reason that there could be a sort of a sense of unacceptability, culturally to do this. And also that there would be, I guess, an understanding of what’s at stake. It’s difficult to do even talking about it tends to give me a little bit upset, the scientists of most deep sea scientists are signed a letter basically begging for a moratorium of at least 10 to 30 years to be able to study even what the risks are of it. But it’s unclear that anybody is listening.

And like you said, having it come where it does in the book, after you’ve just spent so much time showing us the wonders that these depths have to offer us. It. It’s striking. And it’s a stark reality that we have such an opportunity to learn and grow and explore these steps. But like we’ve done with so many other things, we have to take action on it now. Because we’ve already we’re already seeing the effects of climate change on our world. And we can’t keep going blindly sort of towards Well, it’ll sort itself out, we thought the oceans could sort it out. And clearly, we need to do more, we need to understand more. And I think knowledge and expanding what we’re used to seeing as affecting us is one of the only steps that most people can start with. And I think the that the moral of this book, I mean, I walked away hope feeling hopeful, and feeling invigorated and impassioned. And I think that that is something that people are really going to find the most promising about this book is that feeling that they walk away with?

The one thing I should point out, too is the deep ocean is by far the biggest carbon sink on the planet. I mean, it is the reason why the temperature hasn’t gone up like from seven to 11 degrees. I mean, it absorbs I think it’s 93% of our excess heat and 30% of our carbon dioxide emissions. And so yeah, let’s tear it up to have an electric car battery. I mean, it’s just, it’s really not. And this is a moment when we could change course and think, step back and think, what are we doing, you know, for future generations like, this is not the thing to do. This is just, as I said, it’s a wisdom test. And if we go ahead and do this, we will have failed it. And I dearly hope that doesn’t happen. I really do.

And especially when you see, like you said, what is at stake, and there is so much awe and splendor in these deep sea, places in the volcanoes and these life forms that I just can’t imagine how if you see those things, and put yourself in the position to understand those things, you would make a choice that isn’t the right one. But I know that money, obviously, you know, many different political and economic factors weigh in, but I think that doesn’t translate to most people, I think the regular person would understand hopefully a little bit better.

Yeah, I mean, I haven’t even really talked, I do in the book, but I haven’t talked about microbial life, which is by far the most potent biological force on the planet, and most of the microbial life is in is in the ocean, and the disruption to the it’s like the DNA, it’s like the Earth’s DNA reservoir, it’s a genomic creativity, it reaches deep into the past. So the amount that we could learn from studying it is, is extraordinary, we’ve only just scratched the surface of this. But one fact that really, I think gets us across is that scientists took samples of the sediment in the seafloor, and it’s completely alive with this microbial life, there’s just because we can’t see it doesn’t mean it’s not really holding up the whole planet. Okay, so they took the samples, and they sequenced them genomically, and came back with like 2 billion DNA sequences, and then analyze those some more came up with 100,000 DNA variants. And of those 60% of them were not merely new species, or new families or generic anything like that they were new forms of life, new branches on the tree of life. So the idea that we would some how go down there with giant vacuum cleaners and suck up the stuff or grind down these hydrothermal vents. And just so we can get a bit of nickel, the real tragedy of is we won’t even know what we’ve lost. It could be the very thing that we need in the future to keep us alive. We don’t know.

And, and that is truly the most frightening thing. But I think going beyond that, I know that as I was reading sort of that ending chapter, those last bits, I had to sort of take a moment and sit and pause with things because it is truly daunting, that and the sort of tectonic situation near the Pacific Northwest, those things all together, get me a little, a little panicky. But I have to remind myself that that is only one small fraction of what is to be taken away from this whole thing is that, yes, there are some terrifying pieces. But there is also so much hope and beauty and wonder that I can let myself ingest and sit with because putting all those pieces together. It’s an incredible experience to go through this whole book and to have all the different ups and downs that are there.

Yeah, I mean, people don’t often realize or think about I think sometimes just the geological drama that goes on on the seafloor and 75% of Earth’s volcanism is there, that is where the tectonic plates meet, which is, you know, at the bottom of the ocean, there are these hadal trenches named after Hades, the kingdom of the underworld, the god of the underworld, those are the where one tectonic plate is colliding with another one is driven downward, it goes back into the mantle. And they create this, these deep V shaped trenches, like the Mariana Trench is one that a lot of people have heard of, but there are others around the world. And they range from the sea floor sometimes is 6000 meters, but the hadal zone starts around there, so it’s just 2% of a footprint, but it’s like 45% of the ocean is filled out there in these cracks between these tectonic plates. On the other side of the tectonic plate. It’s pulling away. So the Earth’s mantle is coming up with magma, and there’s a 40,000 mile chain of mountains, rift volcanoes volcanic events that encircles the entire planet. It’s the biggest geological feature on the planet is called the mid ocean ridge. Just kind of like this, this jagged line that like seams on a baseball and in those areas microbes come out of the mantle, you know, volcanic activity, lots of seismic activity and both at both ends of the plate, whenever you see a big tsunami, it’s usually caused by the subduction like in the trenches. So it’s really important that we understand what’s going on. And the most amazing thing about this is that when they first noticed that the seafloor was spreading, where the plates are moving away from each other, and new seafloor was being formed, they thought, well, the earth must just be expanding. But what they didn’t realize, and they eventually came to find is where it goes down where its ducks into the mantle, the plates, that’s not that’s colliding and being forced downward, it’s an exact equilibrium. So I mean, that’s just to me is one of the extraordinary things that we don’t often think about. But it’s what makes this place so special, so hospitable to life, you know, makes our own existence possible. Every bit everything’s existence possible, everything alive.

And those are the things that I think maybe we learned about here and there in school, or maybe we’ve heard, you know, on a nature documentary that we were half listening to, but to really engage with that notion that our planet is this perfect source of life, and that we are, you know, interacting with it in that way to sit with that and to think about that really does change your perspective on how you exist on the planet, which sounds very, like grandiose, but I think that that’s what many of the scientists and the researchers that you’ve worked with, that’s what they live every day, is that never ending curiosity that never ending exploration that is so magical about our world.

Yeah, I mean, I find it endlessly fascinating. And the notion that we’ve only mapped at high resolution 25% of the seafloor, if you look on Google Earth, you can see the seafloor, but it’s very low resolution. And so what happens, what happens is when they have a sonar array, which to do it at high resolution, you have to actually go over top of the area, tow it behind a ship or on a ship, they find it’s like putting the lens on the Hubble telescope, and they find like, hundreds and thousands of more sea mounts and volcanoes then have showed up at the lower resolution map. So what I talked about in the beginning of the book is another thing that got me really excited as when they began to search for the missing flight MH 370, the one that just appeared in the Indian Ocean, they realized that the Indian Ocean, the seafloor was virtually unknown. So they before they could really search for it, they had to do these high resolution maps. And that particular part of the Indian Ocean is just extraordinary. It’s very old. It’s where the continent supercontinent Gondwana tore apart. They’re like, everything is extreme down there. And these maps were just like revealing this lost world. And it just raised the question again, like, what else don’t we know about that’s down there? You know, everywhere we look, there are extraordinary things we had no idea about. So to me, that’s really exciting.

I couldn’t agree more I was I left this book feeling very excited. And again, I had to do a lot of my own Googling and a lot of my own talking to people and you know, I’ve with varying degrees of success on the talking to people. But I guess sort of one of the things I want to do to wrap up because I have learned so much even just from this conversation is who is your perfect reader for this book, who do you hope finds this and sort of takes it home and delves in.

I always have the same perfect reader and it’s somebody who is as curious as I am, somebody who wants to go on a wild ride to and learn things and have fun and meet people. It’s basically, I always see myself during my reporting, I’m a proxy for the curious person. I’m not a scientist, I hang out with scientists a lot. I’m sort of a science groupie. But you know, I really stand in for the curious person who’s like, what do you mean that blank fill in the blank? What do you mean, there’s like, a last city that was named after Atlantis in the middle of the Atlantic? So yeah, that’s my perfect reader.

And do you have a favorite fact or something that you feel like people really just need to know, something that surprised you? As you were writing, I could list like 7000 things, but I’d love to know yours.

I mean, I mentioned it before, but I do think it’s really interesting that in the twilight zone, there are more creatures in life than there are the rest of the layers of the ocean combined. And it’s only a 2000 foot from 200 meters to 1000 meters. So it’s pretty thin compared to say the abyssal zone which is from 3000 meters to 6000 meters are the hadal zone which is from 6000 meters to 11,000 meters. So it’s it’s this band of like raucous life down there and it is also doing the majority of pumping carbon so these little creatures that live there every night, they travel further upwards to closer to the surface and eat phytoplankton, those Sun nourished plants, and then they swim back down and excrete it and it gets sequestered. So they’re a biological carbon pump, which is also this is maybe the coolest fact is that it is the world’s largest animal migration happens every single day, and it’s a vertical vibration. So to me, it’s just this extraordinary thing that most people don’t realize that it’s there. And it’s also, as I said, extremely beautiful to look at.

And if that doesn’t pique, reader’s curiosity, I don’t know what will because this book is such a perfect mix of facts and beautiful writing. And I really felt like I was there for so much of this. I changed my perspective on things. It taught me so much. I can’t wait for readers to get their hands on it. Susan, Casey, thank you so much for being with us here today. And everyone needs to go pick up The Underworld. If you have any curiosity about the ocean, which I think so many people will right now. It will teach you more than you ever thought you needed to know. Thank you.

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Poured Over: Susan Casey on The Underworld

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