Unexplainable - The deepest spot in the ocean

Episode Date: June 12, 2024

Seventy-five percent of the seafloor remains unmapped and unexplored, but the first few glimpses scientists have gotten of the ocean’s depths have completely revolutionized our understanding of the planet. For show transcripts, go to vox.com/unxtranscripts For more, go to vox.com/unexplainable And please email us! [e-mail] We read every email. Support Unexplainable by becoming a Vox Member today: vox.com/members Please take a second to help us learn more about you! vox.com/podcastsurvey Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Dive, dive, dive. And we slowly make our way down. I'm just sitting there and like, oh my gosh, it's happening. You know, it's happening. And so I'm just staring at the windows, small circular windows. and just seeing the light blue color of the ocean surface, just slowly changing colors, light blue to blue, to like navy blue and then to black, black all the way down.

It's unexplainable. I'm Noah'm Hassanfeld. Last week, we went up to the highest place in the world, depending on how you define it. But this week, we wanted to explore as far as we could in the opposite direction. the deepest part of the ocean floor. There's so much that we need to learn, and there's so many things that we don't know about the ocean. Currently only 20% of our seafloor is mapped.

Nicole Yamase is a marine biologist from Micronesia, which is home to the deepest part of the ocean, the Challenger Deep. I've always been surrounded by the ocean. I was born in Punepe. Every weekend we'd always go swimming in the ocean or go to the rivers and waterfalls. And my mom said my first boat ride was when I was three months old.

So they just wrapped me up and brought me out. More people went on the Apollo missions to the moon than have been to the Challenger Deep. But Nicole got the chance to be the first Micronesian person to go. So I was like, heck yeah, I'll go down. This part of the ocean is so unknown that every visit can lead to a new discovery. And the specific spot that Nicole visited with expedition leader Victor Viscovo is so remote that no humans had ever been there before. Nicole and Victor's eyes were the first to see it.

The Challenger Deep is located at the southern end of Mariana Trench. It's as deep as you can go on the planet. It is the deepest trench and one of the longest trenches in the world, and it's where the tectonic plate of the Pacific actually rams into Asia. Victor Vescovo is the owner of the limiting factor submersible. It looks like a tooth. It's like hanging off the side of the ship in the back. And there's a little railway that we get to walk on and enter the hatch.

It's like going down a slide, but you have to like slowly step on these little handles where you make your way down into the limiting factor. In the center is a titanium ball. It's 90 millimeters thick. That's what Victor and I were sitting in, and that's what. keeping us from being crushed by the pressure down there. It's eight tons of pressure per square inch. So imagine four regular-sized automobiles on your fingernail.

And that's over the entire submarine. And so the entire submarine is subjected to an enormous amount of pressure equivalent to three aircraft carriers on top of it in the water. It's actually easier to go into space than it is to actually go to the bottom of the ocean because of the incredible harshness of the train. So it's quite a technological marvel. It's like you're sitting on a two-seat airplane. Victor is literally sitting right next to me on my left side.

Right in front of us are three small windows with little screens that allow us to see what the cameras are seeing outside. It also has lots of all the buttons right in the back of us. On the top of us right here are the oxygen bottles. And right above us is the hatch that they close. We're good in here. Once we got in, you know, we said our goodbyes. Dive, dive, dive.

Victor turns on the propellers and we slowly make our way down. I'm here with Nicole Yamase of the Federated States of Micronesia. I'm Victor, as always your pilot on the limiting factor. Currently over the western pool of the Challenger Deep. Pretty excited. I feel really calm. I was just reflecting this morning and I feel like I'm going home. I'm looking at the screen and you can see you can see. just see the depth just getting deeper and deeper and deeper.

And you really don't get a sense of motion of going down other than just watching that depthometer keep going down and down and down. Victor would be like, okay, we have two more hours, we're halfway there, okay, one hour. And then the moment he says, okay, we're like 200 feet. From the bottom, I go, no way. You know, I started freaking out. Like, I just kept looking at the window. And he goes, we're here.

I go, no. It's starting to get lighter. You can see it. What? Is that the bottom? That's the bottom. That's the bottom of the Challenger Deep. Like my eyes, I didn't believe what I was seeing.

Congratulations. Welcome to Challenger Deep. Oh my gosh. I was just freaking out. But in that moment, I was just like, holy moly. Surface, LF, depth, 108. Nine or eight. I still can't fathom the depth that we're at, like 6.8 miles.

I was like, holy moly, that is deep. Just the feeling of, you know, being at that depth, we're literally a tiny dot. If you think how vast the ocean is, you know, we were the first set of eyes to see this location. And the bottom, there's just nothing. Just flat, untouched, fine silt. I'm looking at the fine silt. Because I study shallow reef macroalgae, I wanted to see whether the organic material of plants

made it all the way down to the Challenger Deep. You know, how much plant material made it all the way down to the dark. Once we got down there, in the Challenger Deep, you know, there's marine snow. It's like organic material. It could be like dead plant material, dead animal matter. It really looked like it was snowing down there. Just tiny white particles you can see in front of the window. Everything is connected even though they're so far apart from the surface and the bottom.

Macroalgae or marine plants could be a source of energy for life all the way down at the bottom of the Challenger Deep. Like this could be feeding the microbes, the animals that filter the bottom. That's why I wanted to try and collect some sediment samples. So I took back whatever I could because, heck, that was stuff from the bottom of deep. So I was like, yeah, give it to me. I'll take this brown slush. You know, I'm still trying to analyze these samples from the deep and see what these very precious samples can contribute to what we know now.

We spent two hours there, and I took out my canoe, hand-sized model, canoe and took a picture of it in front of the screen that showed the depth. That canoe was my dad's canoe and that really represented a lot of me, a lot of significance because my dad was, you know, the first person to inspire me to go into marine biology. And the canoe represented Micronesia, Pacific Islander, and it also represented navigation. You know, as a Pacific Islander to be the first one to go down, I didn't want this to just be, you know, my expedition. I wanted it to be our expedition. So this was an accomplishment, not just for myself, but for everybody.

I always say the ocean is vast, but holy moly, I've seen it. I've seen it from the top of the sandy shores all the way to the bottom of the fine silt Challenger Deep. It's just amazing how we just don't know so much and just, to know that it's in my backyard. It was always there and I never knew about it. It's just like makes me even more excited to not only keep my studies in the shallow, but even explore more deeper and see how they're connected. I think that's it.

That was fun. Goodbye. Up we go. Surface, LF, surface, weight, released, ascending. What Nicole saw is just one. spot in the Challenger deep, which is itself just the tiniest fraction of the unknown that is the seafloor. After the break, we zoom out to take on the rest of that unknown, how one woman's mapping project completely transformed the way we see our planet.

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Canada's car marketplace. Unex to laugh at safety. Now they call me. Unexplainable from the Vox Media Podcast Network. Unexplainable, we're back. Before the break, we were hearing from Nicole Yamase, who visited the deepest place in the ocean, the Challenger Deep. And now I'm here with producer Mandi Nguyen, who actually spoke with Nicole for this episode.

And Mandy, you know, this sense of the unknown that Nicole was talking about in the Challenger Deep. Is that exceptional? Or is that sort of true for the rest of the seafloor? I mean, when it comes to the ocean, we've barely been anywhere. Like, it's just so vast. And so it's not just the Challenger Deep that we don't know that much about, but the rest of the sea floor, you know, like the ocean floor is 70% of the ground cover of our Earth, but only 20% of it is mapped.

So the rest is just like a big question mark. Yeah. And do we have any idea what is lying in that question mark? I mean, I assume it must have, I don't know, like huge secrets, right? Yes, it does. It's like understanding the contours of the seafloor and what's there really helps us understand our earth. Like it impacts, you know, weather and the climate. But also when it comes to mapping the seafloor, just to kind of give you a sense of how important that is, when we first created like a comprehensive map of the seafloor, it completely revolutionized science and completely changed how we saw our earth.

How long ago was that? Was that recent? Or was that a long time ago? It was actually only in the 50s. For most of modern history, measuring the seafloor meant scientists going out at sea and then throwing out these lines with weights at the end, waiting for the weights to hit the bottom and then measuring how much line went out. So every time they wanted to get a measurement, they would throw a line in with a weight and just kind of like see how long that line is until it hit the bottom? Yes, so it was really tedious and, you know, it took forever.

And it wasn't until World War I that there was a number. development of sonar, which allowed us to map the seafloor with sound. And scientists could, for the first time, like, systematically measure the seafloor. And one of the first scientists who used the sonar to create detailed maps of the seafloor, her name was Marie Tharp. This is an interview with Marie Tharp. Today is September 14, 1994. Marie died in 2006, but she recorded a series of oral histories.

How far back do you want to go, sir? She worked under a scientist named Bruce Heisen, who would go out on ships at sea and he would collect sonar data of the seafloor. He would be on these ships that would send out a ping and then they would wait for the echo to return. And basically, the longer it took for the echo to return, the deeper, the ocean, wherever they were.

I imagine that would take a long time again to do the entire ocean, right, to do any sort of big area? Yeah, because they could only have a bunch of data points along the path of a ship, which allowed them to kind of trace the contour of the sea floor in whatever little sliver that they were sailing on. So the depth is some number here.

And as they went forward, they'd be like, oh, now it's 2,000 feet higher. So maybe the ocean's going down here. It's going up there. Like there's a valley under this part of the ocean. There's a mountain under this part of the ocean. Is that how it works? Right. And Marie was the one in charge trying to make sense of the numbers.

Like she was the one connecting the dots so that she could string them together to make a silhouette of the seafloor along the ship's path across the Atlantic Ocean. Marie and Bruce, they collaborated on six of these profiles or silhouettes of the seafloor from six different expeditions. We had the six profiles. And we just suddenly, one night, got the idea to put our horizontal profiles into, the form of a map. And Bruce made this preliminary sketch, and then he handed it to me,

he says, well, why don't you fill in the rest? Marie used her geology knowledge to kind of fill in the gaps, because again, she only had these six cross-section, these six like side profiles of the entire Atlantic Ocean. And so she's like, okay, it looks like there's like a mountain here, there's these deep valleys and canyons here. It's kind of like drawing someone's face

from just a silhouette of their side profile. Okay, not easy. Exactly. And as she was making these maps, she noticed something pretty big, like something spanning the entire length of the ocean. But it was also just very strange. Well, I found a mountain ridge, and then we found the crack. The crack? Yeah, she had basically found this gigantic crack running down the middle of the North Atlantic Ocean.

And as she and other scientists were working through this discovery and trying to make sense of it, She noticed that this crack was the epicenter of hundreds of earthquakes. What does that mean? Is that important? Yeah, she had basically discovered the mid-Atlantic ridge, which is the seam of our earth in the Atlantic Ocean. It's where the North American and Eurasian tectonic plates are pulling apart from each other, which creates like a crack. Magma comes out and pushes these slabs apart, which then solidifies mountain ranges on either side. Whoa. And, like, you know, it's not just cool.

It was also a really big discovery because Marie had found evidence for continental drift theory. That's the idea that all the continents are slowly moving, and they used to be part of one big supercontinent. Yeah, which we note now because they're attached to these tectonic plates, which are constantly shifting. So the continents themselves are also slowly shifting. But at the time, continental drift theory was like a pretty fringe idea. Continental drift had been rebuffed for 40 years or more, violently rebuffed. You could get fired for believing it. You could get fired for believing in continental drift theory?

Yeah, there was just lots of anti-drift culture in academia at the time. Anti-drift culture? Yes. Like even within Marie's research center, like Columbia University where she worked was apparently a big center of anti-drift culture. Why was Columbia so anti-drift? Well, academia in general was anti-drift because the guy who proposed it and heavily advocated for it, he wasn't a geologist, so it was very easy to dismiss. But also there was limited evidence for like how continental drift could be true. Like, you know, the earth seemed pretty solid, the continents.

They didn't seem to be moving or going anywhere. Makes sense. Yeah. And in addition to all this anti-drift culture, when Marie first brought her findings to Bruce, he dismissed her ideas. as quote-unquote girl talk. Seriously? Yeah, it was pretty ridiculous. Marie had it pretty tough as a woman in the sciences at the time.

You know, she wasn't even allowed to go on expeditions out at sea because women out at sea were apparently bad luck. And even when she was able to go out on sea, she was relegated to doing paperwork. That was what I usually did when I went on any cruise paperwork, being a girl. Marie eventually won Bruce over on the existence of this huge rift, this crack running through the Atlantic Ocean.

And when they shared their seafloor maps of the North Atlantic with the scientific community, it caused a lot of controversy. They said it was a bunch of lies, and no one believed our rift valley, even in 1959. But Marie and Bruce, they kept making maps, and as more of their maps came out, the evidence was pretty impossible to ignore. even though Marie's name wasn't on the early papers. It's a revolution. It compares with the Copernican revolution.

Galileo only suspected that the sun was the center of the universe and not the Earth. Copernicus proved it with a telescope. Once it was proved, that was a big revolution. Man was no longer the center of the universe. That was something. So we contributed to... to a revolution in geological thinking, because now they're using the ocean in plate tectonics

to redo the geology on the land. It's created a revolution. It's kind of hard to overstate the kind of scale of information that she gave us. Like she allowed scientists to start understanding how the earth moves, how it's shaped, how it was formed in the first place. Yeah, it's almost like,

You know, we did this episode on Henrietta Levitt a couple months ago, where, you know, just by measuring the distances to stars, she transformed our understanding of the universe. And this just feels like so similar just by mapping the seafloor, Marie transformed our understanding of how the world works. And we thought that was pretty important because you could only do that once. You can't find anything bigger in that. So how much of the seafloor did Marie end up mapping?

So she ended up creating the very first comprehensive and accurate. map of all the world's oceans, but most of that was created based on prediction. Boy, we did a lot of guessing. Is that sort of how Marie was able to make this map of the floor of the Atlantic Ocean using just those six cross sections? Yeah, she had very limited data. So there was like a lot of gaps to fill in. You know, back then, they could only make really good guesses about what was in those gaps

on the seafloor compared to today where we can really map the seafloor in detail. Right. Like you said we've mapped, what, 20%? Yeah, currently. And like, this is a really recent development. Like, even in 2017, only 6% of the seafloor was mapped by modern standards. So you're saying like 14% of the ocean floor has been mapped in the last four years. Yes. And 6% of the ocean floor was mapped in all of human history before that. Before that, yes.

So we're really like speeding up here. I mean, could we map the whole thing soon? I think it's realistic to expect a map of the seafloor within our lifetimes for sure. So I spoke to Vicki Ferini. She's a senior research scientist at Columbia University. Where Marie Tharp did her work? Great department. Right?

And Vicki was telling me that this recent, like, explosion and ocean mapping comes from technological advances like underwater, drone-type vehicles that can swim around by themselves and take measurements. Or something called multi-beam sonar, which is, Sonar that can cover a lot more area in a lot more detail than the sonar that Marie was reading off of. Okay. But in general, most of what we know of the seafloor, most of that is coastal, so not the deep, deep sea. I mean, there's so much about how the planet works that is basically preserved in this sort of underwater museum that is the deep sea. What kind of potential mysteries are hiding out there, do you think?

I mean, there's so many. Like, the shape of the seafloor influences how deep ocean currents work in ways that we don't understand yet, which then influences our climate. Half of the oxygen and the atmosphere comes from the ocean, from the organisms in the ocean. So we're all really deeply connected to it. It doesn't just cover the majority of our planet, but it affects a lot of what we do in our daily lives. And we just don't know what we don't know, you know. Maybe we won't necessarily discover the next continental drift, but there's a lot of blank space to fill in. I mean, it just feels like we're right at the beginning of this huge task of understanding. I mean, what I guess is just the vast majority of our planet. Yeah, we really are.

Like, getting from 20% to 100%, like, who knows what else we're going to learn and what we're going to find, you know? The ocean is so close, but the seafloor is so hard to get to, especially in these very deep places. And it makes me wonder if I could ever go there, if I could ever see the Mid-Atlantic Ridge or these wild underwater landscapes. Like, it's kind of exciting thinking about not just what we haven't mapped, but what we haven't even observed or explored. How could you not be excited about it? You know, people have this passion and enthusiasm for outer space, which is talking about. totally understandable, but the ocean is equally, if not more, exciting to me because it's here. It's the same planet that we're on.

It's equally difficult to get to and to explore, and there's infinite mysteries to be revealed. We originally aired this episode back in 2021, and in the last few years, we've mapped another 5% of the ocean floor. Only 75% more to go. This episode was produced and reported by Manding Wynne, and Meredith Hadnott. We had edits from Bird Pinkerton, Brian Resnick, Jillian Weinberger, and me, Noam Hassenfeld. I also did the music for the episode.

It was mixed and sound designed by Christian Ayala, in fact-checked by Mandy. Special thanks to Nick Verola and Caledan Oceanic Verola Media for footage of Nicole and Victor's Dive. And thanks to Ronald Dole and Tanya Levin. Marie Tharp's oral histories came from the American Institute of Physics and Columbia University. You can support this show in all of Vox's journalism by joining our membership program today.

You can go to Vox.com slash members to sign up. You can also support the show by leaving us a review or a rating, which really helps us out a lot. And if you have thoughts, please email us. We're at UnexPlanable at Vox.com. Unexplainable is part of the Vox Media Podcast Network, and we'll be back next Wednesday.