Episode 5: The gateway to secret underwater worlds

With the invention of scuba diving, Jacques Cousteau opened up the deep sea to humanity and left a legacy that continues to drive underwater exploration today.

Jacques Cousteau wears his iconic red diving cap aboard his ship Calypso, circa 1970s.
Photograph by The Cousteau Society

When Jacques Cousteau was young, an accident sent him on a path that led him to invent scuba, opening up the underwater world to humans. Today, scuba explorers like David Doubilet and Laurent Ballesta follow in his footsteps, making discoveries on their own amazing and sometimes terrifying adventures.

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LAURENT BALLESTA (PHOTOGRAPHER): We're in the middle of winter. So the water is very cold, and the sky was gray and the sea was gray as well—with no limits, you know, and you see the sky and the sea. The sea was very flat. There is no limit between the sea and the sky.

PETER GWIN (HOST): That's Laurent Ballesta, a French photographer. He's remembering one day he spent out on the Mediterranean, when he was a teenager living in Montpellier. It was a day that would change his life. A fisherman had told him and a friend about a nearby shipwreck, and they were searching for it along the shore.

BALLESTA: And so then I start to see some fins—big shark fins.

GWIN: The fins came a foot or two out of the water. It was incredibly strange because the sea near his town wasn't supposed to have sharks.

BALLESTA: And I said, My god, what's that? One big fin like that. Another one. Another one. And the sea was full of these fins.

GWIN: There were about a dozen sharks, and each was about18 feet long—
the size of small boats.

BALLESTA: So that was huge.

GWIN: But even though he hadn’t seen sharks here before, they looked familiar. Laurent's hero was the iconic French underwater explorer Jacques Cousteau. As a kid, Laurent used to swim around pretending to be Cousteau. But now that he was looking at real sharks, it was like Cousteau was guiding him.

BALLESTA: And of course I never see that before, but I read so many books about marine life, and so, so many documentaries from Cousteau, of course, that I knew exactly what it was.

GWIN: They were basking sharks. And they feed on plankton, not humans.

BALLESTA: And so [to] my friend, I said, OK, I go into water; it's safe. And I went in the water. That was an amazing feeling.

GWIN: And so Laurent swam with the sharks, just like his hero, and he got to see them up close.

BALLESTA: There is a lot of parasites in his body. A lot of little fish swimming around, even part of a net on his fin. You know, it's like a little planet.

GWIN: He spent three hours swimming in the frigid water with this school of basking sharks, watching them as they interacted with the sea life around them. Afterwards, he went home to tell his family about this amazing adventure, but he didn’t get the reaction he expected.

BALLESTA: I was diving with five-, six-meter-long sharks this afternoon. And I saw in the eyes of my parents and my brother that nobody believed me. He said, Oh yeah, of course, of course, of course, you dive with big shark. Of course, of course.

GWIN: But this experience made Laurent realize something.

BALLESTA: You cannot be Cousteau or you cannot play like if you were Cousteau or act if you were him, if you don't bring back images—and good images. And so I say, I have to prove—my talk, my telling stories, is not enough—won't ever be enough.

GWIN: I’m Peter Gwin, editor at large at National Geographic magazine. And this is Overheard, a show where we eavesdrop on the wild conversations we have here at Nat Geo and follow them to the edges of our big, weird, beautiful world.

This week we’re going to venture to some of the biggest, weirdest, most beautiful and—largely unseen—parts of our world, hidden deep beneath the oceans.
We’re going to look at how we’ve learned to explore these remote places, and we’re going to follow Laurent in search of a fish that supposedly disappeared with the dinosaurs. It’s a creature scientists say changed life on land.

More after the break.

GWIN: To talk about humans exploring the underwater world, you have to talk about Jacques Cousteau. Of course, people have been swimming and diving for as long as they’ve been living by the water. And over the centuries, we’ve devised various ways to peer into the depths. But it wasn’t until the 1940s, when a skinny French Resistance fighter came up with a way to allow humans to breathe underwater.

See, before 1943 people who wanted to explore underwater had to use a snorkel, which meant you couldn’t go very deep, or you had to put on a heavy suit and wear weighted boots to walk around on the seafloor, breathing out of a tube that went all the way up to the surface. And the view wasn’t great. You had to peer out from a steel helmet that had a little window.

DAVID DOUBILET (PHOTOGRAPHER): It was small, like a porthole, and it had a kind of a set of bars in it. So if you fell down, you wouldn't break the glass and then drown.

GWIN: That's David Doubilet. He’s been a National Geographic underwater photographer since 1971, and like Laurent, he’d grown up idolizing Jacques Cousteau.

DOUBILET: But it was like looking through a Tudor window and seeing a vague landscape on the other side.

GWIN: And if you wanted to take photos down there ... well, it’s almost always too dark for a diver to take a photo. So early underwater photographers came up with elaborate ways to capture images. David says a diver would go down with a camera and find something to photograph. And then a person on a boat floating above would take out a special explosive and set it off in the water.

(Sound of underwater explosion.)

DOUBILET: And it made an enormous amount of—it was as bright as a couple of flash-bang grenades that they use to take over airplanes—terrorists.

GWIN: And then, in that light, the diver would snap the photo.

DOUBILET: And they never knew when the flash powder was going to go off.

GWIN: It was ridiculously dangerous. And if that weren't enough, the oxygen going down to the diver was risky too. When Cousteau was a young man, people would use a hose to run oxygen from the surface down to divers. The problem is when oxygen gets deep enough ...

DOUBILET: It becomes toxic, and it can cause convulsions and death.

GWIN: While in the French Navy, Cousteau went deep underwater with that dangerous straight oxygen. He also had a particular sensitivity to oxygen underwater, and so he had convulsions and was pulled from the sea, unconscious.

DOUBILET: And Cousteau went through that twice in his life. And that was enough for him.

GWIN: So he invented something called the Aqua-Lung. It was a device that a swimmer could put on their back—like a backpack—and it would deliver air directly to the diver, letting them swim around. Other people had built similar devices, but the Aqua-Lung had a unique regulator that controlled air pressure. Here's Cousteau describing that invention at a National Geographic Society lecture in the mid-1960s.

JACQUES COUSTEAU (FILMMAKER): Here you can see our first mask that they made in 1936 of an automobile inner tube and a glass plate.

GWIN: We now know Cousteau’s Aqua-Lung as the self contained underwater breathing apparatus, or scuba. And unlike the old options, the scuba system just worked. The diver wouldn’t be stuck walking on the seafloor. Instead, he or she could actually swim around, freely.

DOUBILET: It's as simple and elegant as a doorknob. It doesn't fail.

GWIN: With scuba, swimming freely underwater was finally possible.

(Sound of rebreather.) 

DOUBILET: You are flying. You are weightless. When divers explore a shipwreck, unlike mountain climbers, they're not climbing up the side of the ship. If you want to see the bridge, you simply fin up to the bridge. If you want to see the keel, you fin down. You’re flying.

GWIN: Swimming like that, like a fish, that’s what Cousteau had been waiting for.

DOUBILET: He was a pilot before he was ever an undersea explorer. But he said after the first Aqua-Lung dive, he said, I never dreamed of flying again.

GWIN: Scuba was a major breakthrough for all divers—certainly for explorers, scientists, photographers. But really it was a profound advancement for all humans.

DOUBILET: And if you back away and look at what the Aqua-Lung regulator means, it meant a passport to 70 percent of our planet.

GWIN: The invention completely changed Cousteau's view of the world. Here he is talking at the National Geographic Society in 1966 about how scuba altered how he saw the planet.

COUSTEAU: When going into the water, at a few hundred yards from a streetcar, I found myself into the jungle with hoards of wildlife, even in the Mediterranean where—that has been overfished for centuries.

GWIN: Using his invention, Cousteau began to focus on documenting this underwater world, traveling on his boat, the Calypso. He showed people places that had been inaccessible and creatures that had been previously unknown. This is a lecture he gave at National Geographic in 1960. He’s showing the crowd photos he took in the harbor in Nice.

COUSTEAU: This is a small, strange fish coming in front. The regularity of this forest astonished the biologists. And then also we could notice that this zone, where these brittle stars were stuck in the bottom like soldiers or like trees. Look at the colors inside these jelly animals, and this one—endless.

GWIN: Sharing experiences and films like this made him a legend. Every dive shop you pass in a strip mall, every YMCA scuba class, every deep-water photo you see on Instagram goes back to Jacques Cousteau.

DOUBILET: And then of course the National Geographic specials, and then all the ABC, wonderful ABC contracts, and that morphed into the TBS contracts, but always with the idea of making a film.

GWIN: As a kid growing up in New York City in the 1950s, David was fascinated by Cousteau’s films. They inspired him to take photos underwater and eventually to make that his career. To date, David has shot about 80 stories for National Geographic all over the world, following in his hero’s footsteps. He’s won awards, published over a dozen books, and influenced two generations of underwater photographers. And once he actually got to meet his hero over dinner at a diving club in Boston in the 1960s.

DOUBILET: And finally I said to him, I have no idea how to begin this conversation.

GWIN: That's how you started? I have no idea how to start.

DOUBILET: I have no idea what to say to you.

GWIN: It seems like a good opening line.

David says that what really got to Cousteau was how much of the underwater world still hadn't been discovered.

COUSTEAU: So this can be done today and we have to start quick.

GWIN: When Cousteau said this, a little boy named Laurent Ballesta was dreaming of the oceans in France. And he was about to take these words to heart in a way that might have even surprised Jacques Cousteau.

More after this.

GWIN: Laurent Ballesta took to heart Cousteau's challenge to explore this underwater world.

BALLESTA: Because for me, from really from my youth, the most I can remember: I will be a diver on his boat, on the Calypso. That will be my life, for sure. No other possibility. I was sure of that.

GWIN: So he went to college in the 1990s and studied marine biology, all the while learning to photograph underwater. And one day, he dove in the French Mediterranean and noticed a tiny, strange-looking fish, about half the size of his thumb.

BALLESTA: It's a fish with a big and large head, quite a thin body. Big fins, very big fins, and it's all dark black, with big white dot on its body. And this dot looks like the Andromeda galaxy—the stars.

GWIN: He took a photo of this spotted fish. And even though he’d studied all the fish in this region, he’d never seen anything like this creature. And he started wondering,
maybe it was a species no one had ever seen before.

BALLESTA: And then I went to see a lot of high-level professionals. Hey, I'm pretty sure it's something new. And some of them say, No, no, no, no, come on. Of course not, you know.

GWIN: People had explored and fished all over this part of the Mediterranean for centuries. And it seemed inconceivable that anyone could find a new fish there. But Laurent persisted, and eventually one of the professors took a second look.

BALLESTA: Fortunately one was say, Oh, maybe—let me try to send this image to some specialists around the world.

GWIN: The photo went all the way to Japan, where there was an expert on this family of fish.

BALLESTA: And even him say, Oh, I don't know this one, I don't know this one. And finally one old professor in England say, “Oh my God, it's amazing. You rediscover my fish.” Oh, your fish? I thought it was mine.

GWIN: It turned out the professor had described the species, which is called the Andromeda goby. But he had described it from a dead specimen. So Laurent was actually the first person to photograph a live one in the wild.

BALLESTA: And so I was very proud. And, you know, it was a very tiny fish—three centimeters. But just with three centimeters, you cannot imagine how many hope that give to me. To say, oh, maybe it's possible.

GWIN: At this point, Laurent was super passionate about underwater exploration and photography, but he was still just a student. And this experience provided a crucial spark.

BALLESTA: But I wasn't sure that my passion could become my job and my life and all these things. And that may be a bit naive, even a bit stupid, but suddenly because of little fish like that, I say, OK, it's going to be my job, for sure.

GWIN: Laurent realized that he’d have to make a name for himself as an underwater photographer. And he had a plan for how to do that. He'd heard about this special fish.

BALLESTA: This fish is called the coelacanth. And it's a huge fish, two meters long.

GWIN: So that’s roughly the size of a harbor seal. But what was so special about this fish? Well, it wasn't supposed to be alive. Most scientists thought coelacanths had gone extinct 65 million years ago.

BALLESTA: Until one was caught in a trawler net in 1938, in the middle of the century. And that was a revolution for a zoological researcher,

GWIN: It's not just that a lost species had been found but this fish offered a window into the ancient past.

BALLESTA: Because this fish was not any kind of fish—it was the fish coming from the family that went out of the water 360 million years ago—and give [rise to] the first amphibian, the first reptile, and then the first mammals. And of course the first human being.

GWIN: This might be the closest thing we could get to our ancient ancestor fish—this link between the oceans and the land, fish and humans—and it was still alive. So finding living specimens became an obsession for scientists.

BALLESTA: It was like exactly the same feeling at this time in the Jurassic Park movie, you know—there is people studying only fossil and suddenly someone come to see them: Hey guy, leave your fossil inside and come with me—I'm going to show them alive.

GWIN: For decades, hardly any coelacanths were spotted. Some were discovered in fishing nets, but they didn't live long.

BALLESTA: It was too deep, too rare, in very few places in the world.

GWIN: You know where this is going, right? Laurent organized an expedition and set off to find and photograph a coelacanth.

BALLESTA: It's the first time I lead quite a big expedition with my own little money.

GWIN: Laurent was betting that he'd be able to photograph the fish and sell the photos. He was excited about the trip, but also nervous. And not just for financial reasons.

BALLESTA: One part of you is very excited and happy to go back down. And one part of you is more and more stressed and scared because you know that these kind of dives are dangerous—mainly when you repeat them every day.

GWIN: They'd be going on a 40-day journey off the coast of South Africa, and they’d be diving down nearly 400 feet. That's really, really deep. Even with scuba gear, the weight of all that water pressing down on your body, especially your lungs, day after day, that can be dangerous.

BALLESTA: You know, you go down, the compression, the compression, the compression every day. It's not very good for your health.

GWIN: Research has shown that repetitive dives like these can increase the chance of a diver getting sick or even dying. So safety was a big issue. But there was also the question of what to do if they actually found the fish.

BALLESTA: Come with me, I say, hey guys, when we'll be down, if we found him, it's not the end of the game. It’s just the beginning.

GWIN: Even if they found the coelacanth, getting a photo of it without scaring it would be difficult.

BALLESTA: So keep cool. I don't want to see any one of you, you know, high five or this kind of stupid attitude underwater, just because we are close to him, just because you will be able to say I did it, you know? No, no, no. Keep humble, keep focus, and make your job.

GWIN: Laurent and his team dove into the water, descending into this dark, cold world—100 feet, 200 feet, 300 feet. He expected this would be a long, arduous search,
but surprisingly after just a few minutes, there it was, right in front of them: A six-foot-long living fossil.

BALLESTA: The coelacanth fish is a big and massive fish. From far, it can look blue, so if you focus on—you point on them a little light, you have these like a cat eyes by night, so it's very weird. From close, it’s more brown, even sometimes a bit red.

GWIN: It was like this armored tank underwater with multiple layers of scales.

BALLESTA: A huge and massive head, with big scales. Every scale—there is three layers of scale everywhere.

GWIN: But the most interesting part was its fins, which sort of look like the beginnings of arms.

BALLESTA: Its fins is not like fins that stick to the body, like the other fish. Imagine there is a kind of very short arm or leg, up to you, and then a fin. And inside this kind of little arms. If you open it—if you look inside—there is already the beginning of all the bones we have—you, me, and all the mammals and the tetrapods on land—have already. The tibia, femur, radius—all the bones of our legs and arms are already in this fish.

GWIN: Laurent is seeing in this ancient fish the traits that would become mammal bones—eventually our hands, our legs. But the task at hand was to get a photograph of this creature he’d been dreaming of for 20 years. And he didn’t want to spook the coelacanth. It was only a foot or two away from him, and what if it suddenly swam away before he could snap the shutter?

BALLESTA: I try to keep inside all my feeling, all my wish to, you know, to not to cry but to, well, and I keep that—just keep focused: It just another fish. Make the best photo you can with the best light, with the best background. Make your job.

GWIN: And when he finally got the coelacanth into his viewfinder, instinct took over. The photo came out beautifully, and he sold it … to guess who?

BALLESTA: By the way, it was my very first publication in National Geographic—U.S. And so I was very proud of that.

GWIN: That was cool, but the experience also made him realize something. It only took him a couple minutes to find this fish that so few scientists had witnessed. It turns out that the fish wasn't that rare after all. It was just deep.

BALLESTA: It mean that the difficult thing was not to find the coelacanth—it was just to reach his universe.

GWIN: Cousteau was right. There were these undiscovered universes all around us, just waiting for us to find them.

BALLESTA: For me that means something. That means it's a really parallel world. And you need a kind of stargate to reach this world so close to you and so far at the same time. One minute, 32 seconds, and I was with a living legend, you know, that's so weird. So many—so many—scientists from the early ’40s and even the late ’30s dreamed about diving with the coelacanth. And they couldn't because it was just 120 meters too low.

GWIN: So just imagine what else is 120 meters (or 400 feet) down, or 500 feet or 600 feet? Most of our ocean world is still undiscovered. Just like Jacques Cousteau opened the door with the Aqua-Lung, if we find a way to go deeper, there are many more worlds to be discovered.

If you like what you hear and you want to support more content like this, please rate and review us in your podcast app and consider a National Geographic subscription. That’s the best way to support Overheard. Go to natgeo.com/explore to subscribe.

If you want to learn more about Jacques Cousteau, you’re in luck. From National Geographic Documentary Films, Becoming Cousteau is now streaming on Disney+.

As we mentioned, David Doubilet has been taking photos for National Geographic for decades. And iIf you want a list of his greatest hits, check out our article “32 Astonishing Photos of A Career Spent Underwater.” And he’s got a new book out this month with some spectacular underwater images. It’s called Two Worlds: Above and Below the Sea.

If you want to see more of Laurent Ballesta’s photographs, you can check out an image he took of a grouper mating frenzy that recently won him the Wildlife Photographer of the Year award from the London Natural History Museum.

For National Geographic subscribers, you can also read about the time Laurent and a small crew of explorers spent 28 days living underwater in the Mediterranean Sea.

That’s all in the show notes.


Overheard at National Geographic is produced by Ilana Strauss, Brian Gutierrez, and Jacob Pinter.

Our senior editor is Eli Chen.

Our senior producer is Carla Wills.

Our executive producer of audio is Davar Ardalan.

Our fact-checkers are Robin Palmer and Julie Beer.

Our copy editor is Amy Kolczak.

And Hansdale Hsu composed our theme music, and also sound-designed and engineered this episode.

This podcast is a production of National Geographic Partners.

Whitney Johnson is the director of visuals and immersive experiences.

Susan Goldberg is National Geographic’s editorial director.

And I’m your host, Peter Gwin. Thanks for listening, and see y’all next time.


Want more?

Learn more about Jacques Cousteau. From National Geographic Documentary Films, Becoming Cousteau is now streaming on Disney+.

See more of Laurent Ballesta’s photographs, including an image he took of a grouper mating frenzy that recently won him the Wildlife Photographer of the Year award from the London Natural History Museum.

Also explore:

David Doubilet has been taking photos for Nat Geo for decades. If you want a list of his greatest hits, check out our article “32 Astonishing Photos of A Career Spent Underwater.”

And check out his new book out this month with some spectacular underwater images. It’s called “Two Worlds: Above and Below the Sea.”

For subscribers:

For Nat Geo subscribers, you can also read about the time Laurent and a small crew of explorers spent 28 days living underwater in the Mediterranean Sea.

If you like what you hear and want to support more content like this, please rate and review us in your podcast app and consider a National Geographic subscription. That’s the best way to support Overheard. Go to natgeo.com/explore to subscribe.