In a deep, dark and unexplored corner of the ocean, researchers are searching for the answer to how all life on Earth began. Take a journey with them.

By our third day at sea, we’d found it: a dozen bare and jagged piles of rock surrounded by ocean the color of Windex. It was smaller than I had imagined, all told, about twice the size of a soccer field. There was no white sand, no volcanic peaks, no palm trees, none of the trappings of other tropical island chains at this latitude, just razor-sharp umber peaks iced in a thousand years of bird shit—the whole of it resembling a kind of sinister Gilligan’s Island.

But we didn’t motor from the coast of Brazil more than 1,000 kilometers (620 miles) across the Atlantic Ocean on a beach holiday or three-hour tour. We came to explore the waters deep below the sunlit surface. We came to collect clues from this place, known as Saint Peter and Saint Paul Archipelago, about how life on Earth first began – and how alien life might evolve on other planets in the solar system.

These are big, serious questions, and we’ve brought a big, serious team to investigate them, including a crew of more than 40 geologists, microbiologists, geophysicists, biologists, engineers, deep-ocean divers and deckhands from a dozen nations. The team will spend the next two weeks aboard the M/V Alucia – a 56-m (184-foot) research vessel operated through the Dalio Ocean Initiative – scanning the ocean floor, sampling rocks, analyzing water samples and diving research submarines a thousand meters beneath the surface.

Nobody has ever explored these deep waters, and no one on the team knows what we’ll find.

“It’s a unique area, and so it might host some unique life systems,” said Frieder Klein, a marine geologist, who’s leading the scientific team from Woods Hole Oceanographic Institution (WHOI). Klein is standing barefoot on Alucia’s top deck in cargo shorts and a faded MC5 t-shirt, squinting in the noonday sun. A few hundred meters to the north, waves crash and fizz on the shores of the 15 bite-sized rock islets.

Klein tells me that below us, millions of years ago, the tectonic plates of the Mid-Atlantic Ridge began splitting apart. This gap has widened by about a finger’s width every year since, which is why Europe and North America are now separated by nearly 7,000 km (4,350 miles) of ocean. Over the course of this very slow process, mantle rock, which usually lies hidden 6 km (3.7 miles) below the crust, has been forced to the surface.

Mantle rock isn’t particularly rare; it covers wide swaths of the deep seafloor around the globe. Here, though, it’s much shallower, much more accessible – and it’s continuing to evolve as it interacts with seawater. “There is really no place like this in the world,” Klein said, wiping his forehead of sweat.

The rock here could also be harboring entirely new forms of life. Klein explains that a chemical reaction between seawater and the iron in mantle minerals creates hydrogen molecules. Microbes, single-celled or multi-celled microorganisms, feed off this hydrogen. These organisms are similar to those that existed on Earth billions of years ago and may be closely related to our planet’s earliest life forms. Klein and his team will seek out microbes in the deep and analyze the chemical processes within the mantle rocks as they occur. In doing so, the scientists hope to catch a glimpse of early life systems – a sort of window back in time to our most primitive selves, and perhaps to our alien counterparts.

“Icy moons of Saturn and Jupiter, Europa and Enceladus, have water below their surfaces; we know that,” said Klein. “And these moons contain the same rocks that are on these islands.” If distant moons in our solar system have the same rock, and the same water, they could have the chemical processes that feed the same basic forms of life here on Earth.

Klein and I peer over the handrail and stare down into the ocean depths that plummet 4,000 m (13,100 feet), the equivalent of 10 Empire State Buildings stacked on top of one another. Suddenly, it feels less like we’re on a boat looking into the surface and more like we’re on a spacecraft hovering over some alien world.

“We’re going where nobody has gone before,” said Klein. The captain cuts the motor and the Alucia gently drifts toward the southern-most islet. Klein gathers his phone and a water bottle, excuses himself, and hustles downstairs. After a year-and-a-half of planning, it’s time to go deep.

It’s a hard thing to fathom, the concept that you, me, the birds and the bees – all life that is and has ever been – came from a few chemical reactions on some ugly rocks a few billion years ago. Proposing such a theory in the 1500s would have likely gotten you beheaded for heresy. Even 50 years ago, it might have gotten you canned from a tenure-track teaching job, or at least ostracized by the scientific community.

That all changed in 1977 when an Oregon State University marine geologist named Jack Corliss chartered a research vessel off the coast of Ecuador and steamed out some 320 km (200 miles) to the Galápagos Trench. Corliss suspected that a volcano, what marine scientists call a hydrothermal vent, was erupting on the deep seafloor in the area. Corliss and his crew deployed a remotely operated vehicle rigged with a camera named ANGUS to investigate. In one particular spot, at a depth of around 2,500 m (8,200 feet), ANGUS’s temperature gauge registered a significant spike. After several hours, the team lugged ANGUS back on deck, cracked open the camera and developed the film.

The 13 grainy photographs that ANGUS had captured when the temperature spike occurred revealed something extraordinary. There was life down there – crabs, mussels, lobsters, worms – all flourishing in complete darkness around a toxic plume of seawater hot enough at its source to melt lead. The incredible pressure, 250 times that on the surface, kept the water from turning to steam. Corliss had found a pressure cooker of life. And not only were all of the animals in this pressure cooker new to science; but, even stranger, they survived in an entirely different biological system.

Unlike surface life, which requires the sun’s light to survive, these life forms lived off the chemical energy in these super-hot toxic plumes – a process called chemosynthesis. Corliss called the place the “Garden of Eden.”

In the years that followed, researchers would find more chemosynthetic communities on seafloors around the world. The deep ocean, it appeared, was not a wasteland but a sort of galaxy composed of independent biospheres, each orbiting around its own life-giving chemical “sun.” And the animals and microbes there had been flourishing for billions of years, perhaps longer than life in the terrestrial world.

Hydrothermal vent discoveries spurred geologists and microbiologists to dig even deeper, into even more extreme environments, on a quest to find the absolute limit of deep life. They drilled 3,600 m (nearly 12,000 feet) through Antarctic ice and discovered an underground lake twice the size of Delaware that has likely been sealed off from the surface for 15 million years. In a single half-liter of water, they discovered thousands of bacteria that could survive in nearly every imaginable environment: extreme heat up to 122 degrees Celsius (252 Fahrenheit), extreme cold to -20 degrees Celsius (-4 Fahrenheit), acidic, alkaline, aerobic, anaerobic and everything in between.

Then researchers plumbed beneath the seafloor of the world’s deepest ocean –nearly 11,000 m (6.8 miles) beneath the surface to one of the most inhospitable environments on the planet. They found twice the amount of microbial life than had been discovered at milder, shallower depths.

They dug into the terrestrial surface as well, more than 4 km (2.4 miles) through the crust to find life forms steaming in water and sulfur that fed not off of the sun, or chemicals, but on radiation from the surrounding rocks. And this stuff had been living there for millions of years.

These discoveries suggest that there is virtually no limit to life. Even at the Earth’s most vicious extremes – from the edges of volcanic calderas to the black water pressurized to 15,000 pounds per square inch to radioactive waste sites – life finds a way. Life persists.

It turns out that in many ways, rocks at the bottom of the deep sea, buried under a mile of Earth’s crust, or covered in bird crap on Saint Peter and Saint Paul Archipelago, aren’t inanimate objects at all. They are undulating, “breathing” systems crammed with organisms so tiny and metabolizing so slowly that nobody ever noticed. Until a few hardy scientists started looking.

Most researchers never bothered. Seeking out extreme life requires traveling to some of Earth’s most far-flung and miserable environments. Only a handful of microbiologists and geologists have had the will, fortitude and resources to endure weeks in the triple-digit heat within African mines, or months in the frozen expanses of Antarctica, or years sifting through the polluted oil fields of Dagestan to find answers.

Which makes it all so much more guilt-inducing for our team to be lounging aboard the Alucia. While the dangers and discomforts of bobbing around in the middle of the Atlantic 600 miles from the nearest hospital are real and many, we’re at least comforted by the borderline luxury of our living and work quarters. Here every square inch of interior space is acclimatized to a refreshing and humidity-free 72 degrees Fahrenheit (22 degrees Celsius) —so brisk that some of us futz around wearing sweaters and socks while the outside temperature climbs toward 100.

Tonight’s dinner, served in the mess hall, includes quinoa, steak, chicken, sautéed green beans, roasted potatoes, farmer’s salad and homemade crème brûlée for dessert.

I grab a plate and scoot next to the two other lead researchers on the scientific team. Diva Amon is a deep-sea biologist from the Natural History Museum of London. She grew up swimming off the shores of Trinidad and Tobago and at an early age was fascinated with the diversity of sea life, especially the animals that dwelled beneath the curtain of permanently black waters. She’s come on the expedition with the hope of finding large-scale chemosynthetic life, such as crabs, tubeworms, shrimp or whatever else may lie beneath.

“We really have not even a basic understanding of many animals in the ocean, especially chemosynthetic life – how they live, where they live and why,” she said.

While the deep ocean below 200 m (650 feet) represents 70 percent of the habitable space of the planet, Amon tells me that less than 1 percent of it has been explored. The largest animal communities and the majority of biomass on the planet live there. And the threats they face are many. Pollution, trawl-fishing, mining and climate change all put this environment and the estimated 750,000 undiscovered species down there at risk.

“We could be destroying the deep ocean habitat, and its inhabitants, before we even know what’s there,” said Amon. “I think it’s imperative to document it all while we still can.”

Sitting beside Amon is Florence “Flo” Schubotz, a geochemist from MARUM Center for Marine Environmental Sciences at the University of Bremen, Germany. She’s come here for the same reasons as Amon, but her interests are smaller: microscopic life living within the mantle rock.

“You think about it, the organisms that live at hydrothermal vents could be some of the earliest [forms of] life on the planet – around way before life on land,” said Schubotz, who is wearing a T-shirt from a past expedition with the Japan Agency for Marine-Earth Science and Technology. “These are ancient systems.”

Schubotz explains that 3.8 billion years ago, there was scant oxygen in the atmosphere. Life relied on other chemicals to survive, including hydrogen, carbon dioxide, and methane. As these primitive organisms flourished, some of them – the cyanobacteria – evolved a type of metabolism that produced oxygen as a waste product. Around 2.4 billion years ago there was enough “waste gas” oxygen to support new forms of aerobic “oxygen-consuming” life. These oxygen-fueled life forms grew more complex, eventually evolving into plants and animals, which eventually became us.

To see these microbes in action, Schubotz hopes to collect samples of deep-water mantle rock and feed it different chemical “foods” such as hydrogen, carbon dioxide and methane to try to spark to life dormant organisms that those samples might contain.

In a sense, she’s hoping to create a few test-tube Jurassic Parks, but instead of a human-eating T. rex, she’ll be reanimating ancient microbes.

The following day, Schubotz, Amon and Klein are standing in Alucia’s mission control, a dimly lit room plastered in wall-to-wall flashing monitors. Everyone is staring wide-eyed at a gargantuan video display of what looks like a rainbow pie with a few pieces missing.

With every passing second, a few more pixelated lines appear on the image and the pie is a little more complete. Klein is entranced, subconsciously “ooohing” and “aaaahing” like a stockbroker watching the ticker of an initial public offering.

What the scientists are looking at is a high-resolution bathymetric map (the underwater equivalent of a topographic map) of the seafloor below us – a rendering of data gathered by the Multibeam Echo Sounder System, a sophisticated sonar device, mounted to the bottom of the Alucia. For the next two days the ship will circle the archipelago, moving farther away with every round, like a needle on a vinyl record playing in reverse. As we pass over the ocean floor the Multibeam will scan every nook and cranny down to a resolution of about 3 m (9.8 feet) and down to a depth of 1,200 m (4,000 feet).

“Nobody has ever seen any of this before,” said Klein. “It’s all very exciting.” He is looking for anachronisms on the otherwise rather featureless underwater cliff. If active hydrothermal vents are here, they’ll likely be marked by telltale spires of carbonate.

Carbonate is a common substance that can be forged from many different processes. Calcium carbonate, which makes up the shells of marine organisms, covers more than half of the ocean floor. The remains of these dead organisms makes up the white stuff in the toothpaste you brushed your teeth with this morning and are in the concrete of the sidewalk you walked on outside your front door.

But the carbonate Klein is looking for is likely not created by biological activities, but from minerals coming out of solution when scalding hydrothermal fluids meet cold seawater.

“There’s something promising here,” said Klein. He points to a peculiar outcropping on the western slope of the island chain. He says it seems unlikely that a rock just tumbled down from above and landed in this spot. It looks as if the structure emerged from the rocks below. “At minimum,” he said, “this area is worth exploring.”

We spend the next few days battling high winds and strong currents. Still, the geochemists are able to take a half-dozen water samples from around the outcropping Klein identified on the map and deeper on the ocean floor. The water in the area has elevated levels of methane, well above what is considered normal. It’s a promising sign.

Some of our planet’s oldest life forms survived on methane and are still found around hydrothermal vents. While some organisms fed off hydrogen and carbon dioxide and expelled methane as a waste product, others fed off methane and expelled carbon dioxide. The combinations and uses may vary, but what we do know is that the presence of carbon dioxide, hydrogen and methane usually signifies an environment that can support primitive life forms.

Which is what made it so exciting to microbiologists when, in April 2015, NASA’s recently retired Cassini spacecraft flew by Saturn’s icy moon, Enceladus, and discovered huge amounts of hydrogen spewing from its surface. Not only that, but the plumes also contained carbon dioxide and other organics, and enough energy to support huge colonies of microbial life – what one geochemist described as “the caloric equivalent of 300 pizzas per hour.”

The chemicals on Enceladus are believed to be produced continuously by vent systems similar to those on our planet, and possibly right below us at Saint Peter and Saint Paul Archipelago.

By mid-morning, Klein and Amon are hoping to find out. On the aft deck the Alucia crew rolls out Nadir, a three-person submarine rigged with half a dozen cameras and lights. We watch from the outside of the sub’s acrylic pressure sphere as Amon, the submarine pilot and a videographer squirm in their seats, unpack water bottles, and ready themselves for takeoff.

Behind them, Klein is seated in Deep Rover, a smaller, more agile two-person submarine. The plan is for Klein to grab as many samples as he can with Deep Rover’s mechanical arms while Amon makes observations of the ecosystem and any chemosynthetic animals that might live there.

Carefully, slowly a crane lifts Nadir, then Deep Rover, over the deck and plops them into the water. A plume of bubbles, a few goodbye waves, and the subs dip below the surface, growing smaller and fuzzier until they disappear.

For the next six hours we’ll sit around, staring at the sonar readouts, waiting, watching and listening for signs of life.

By evening, the Alucia is once again a flurry of activity. The crew is hosing off the subs, Klein is bustling around buckets of rock samples, and geochemists Sean Sylva and Jeff Seewald are cooking up water samples that Deep Rover sucked up from around the seafloor.

On deck, Sylva places a water sample in a gas chromatograph, what looks like a steampunk version of a mid-1980s microwave. Sprouting from the chromatograph’s sides is a rat’s nest of wires, tubes and knobs all held together by wood clamps. The tubes and wires, of course, have a purpose. As the water heats up in the oven, the compounds in the water will travel through the tubes at different speeds, depending on their size. A computer rigged to the device will analyze the speed at which the compounds move, allowing the team to gauge the proportion of methane and other chemicals in the water from that site.

Meanwhile, in an adjoining makeshift laboratory, Klein and Schubotz are inspecting rock samples that Deep Rover grabbed from a depth of more than 500 m (1,640 feet). “I got three ugly rocks, and one big freaking rock,” said Klein, wiping his hands on an old Amoeba Records T-shirt.

Klein puts a rock in my hand and points out a web of tiny veins. He explains that when olivine, a common mineral made up of magnesium, iron, silicon and oxygen, comes into contact with seawater it destabilizes, allowing the water to penetrate more deeply into the rock. These little veins act as rivers for life forms within the rock, delivering energy and nutrients and removing waste. Over time, the olivine slowly dissolves and other minerals form within the veins. This process creates a marbleized rock that the ancient Romans called verde antico, or what geologists like Klein call serpentinite.

“What this rock says is, yes the process of serpentinization has occurred on Saint Peter and Saint Paul Archipelago,” said Klein. “But are we just looking here at an archive of some past process? That’s what we need to figure out.”

As Schubotz and Klein slice and pulverize the rock samples and Sylva and Seewald vaporize seawater, I step outside to the roof deck to get a breath of fresh air. It’s twilight and the night sky is already so wet with stars it looks as if there’s more light than black.

I read a scientific study hours earlier in which researchers described collecting and comparing microbes from some of the most disparate and remote areas of the planet. Nineteen of those microbes were genetically identical, regardless of where they were collected.

Microbes can’t just get up and walk, or fly, or swim from one location to another. And even though some of these identical 19 microbes were separated by more than 16,000 km (nearly 10,000 miles), they metabolized food in the same way, replicated in the same way and shared the exact same DNA. How did all these identical life forms find themselves in these far-flung locations? It would be a bit like finding members of the Osmond family on every planet in our solar system and beyond.

Standing beneath the canopy of stars and moons and planets, I can’t help but wonder: Since we all start with the same basic building blocks, might all life follow the same path? Billions of alien habitats above and below where I stand are made of the same rocks, the same water, and are susceptible to the same chemical reactions that first sparked life here on Earth – and eventually evolved into the hands that are scribbling down these words and the eyes that are staring at those stars.

How many other eyes made from the same stuff, the same reactions may be staring back at us now?

This thought is quaint, for sure, reminiscent of late-night, freshman-year philosophy rants, and most likely fueled by the three cans of cheap Brazilian beer I guzzled at dinner. I get that. But later that night, as I’m lying in my bunk, staring out a port window into a sky dusted with a billion distant stars, I can’t seem to shake it.

It’s our thirteenth day at the edge of Saint Peter and Saint Paul Archipelago, hovering over the Mid-Atlantic Ridge. This is the morning I’ve been both anxiously anticipating and subconsciously dreading since I first signed up for this assignment months ago.

We’ve lost a week or so due to strong currents that have kept the subs onboard the Alucia, but today, the skies are clear, the sun is shining, and the ocean is glass. But I’m also starving and my throat is parched. I haven’t had a sip of water in the past 14 hours and probably won’t eat or drink until later this afternoon. Amon suggested that this all-out fast is the best way to ensure my well-being. “The last thing you want is to, you know,” she paused and shot a knowing a nod. “You just don’t [want to] feel uncomfortable down there.”

By “down there” Amon is referring to the hundreds of meters below the surface I’ll be exploring aboard Nadir over the next several hours. For any adventurer or scientist, or reasonable citizen of the world, this excursion would be an absolute dream. But, sadly, all I’ve been able to think about is what will happen if I suddenly need to relieve myself, or feel claustrophobic or suddenly feel the urge to stretch my legs or arms or back. There are no windows to open a thousand meters below the surface, no bathrooms, no pulling off to the side of the road. I’ll be stuck in a child-sized seat with my legs tucked to my chest for the time it takes to watch The Godfather, Part I. Twice. Including credits.

“You should lighten up,” said Colin Wollermann, a crop-haired American who will be piloting Deep Rover. He’s sitting at a mess hall table across from me, shoveling bacon, buttered bread and eggs into his mouth, washing it all down with liberal gulps of coffee. “My personal approach is just to get as gassy as possible,” he laughed, and takes another bite.

Alan Scott, the pilot for Nadir and Alucia’s submarine team leader, is beside Wollermann, packing handfuls of candy bars and potato chips into a backpack should we get hungry along the way. “It’s easy, mate,” he said in a thick Scottish brogue. ”It’ll go by so fast you won’t even know what happened.”

Strangely, one thing that hasn’t crossed my mind this morning are the dangers involved in cruising around along an unexplored seafloor of the Atlantic in a pressurized bubble, 1,000 m (3,280 feet) below the ocean surface and 1,000 km from the nearest hospital, or airport, or doctor. When I asked Klein if he ever worried about doing this kind of research, he demurred. “The only thing dangerous about it is to have spent a year and a half planning this trip and come home empty-handed,” he chuckled. “The rest of it, riding in subs, sailing out here? That’s the fun part.”

Amon was a tad less sanguine. Days earlier she had told me a story about the Johnson Sea Link, a four-person submarine. In the summer of 1973, the same year the sub was first launched, a team of two pilots, an ichthyologist, and dive master headed out on what was considered a routine dive 24 km (15 miles) off the coast of Key West, Florida. The mission was to recover a fish trap from a sunken destroyer 100 m (330 feet) below the surface.

While attempting to ascend, the Sea Link got caught on a cable extending from the sunken ship. The passengers sat back, relaxed as best they could, and waited for help. With the emergency oxygen reserves onboard, the pilots estimated they had about 42 hours before they suffocated.

Hours passed. The temperature plummeted to 42 degrees Fahrenheit. Soon the passengers were suffering from hyperthermia. Worse, their calculations for fresh air were far too optimistic. The concentration of carbon dioxide in the air began to rise to dangerous levels.

Eight hours after the pilots called for help a Navy support ship arrived and made several attempts to disentangle the sub. Nothing worked. The passengers began to lose consciousness.

The Sea Link was finally freed 32 hours after it had been launched. Two members of the sub team were dead of carbon dioxide poisoning; the other two were treated immediately and would live.

While the Johnson Sea Link was an extremely rare disaster and happened more than 40 years ago, it’s impossible to overlook the fact that diving hundreds of meters deep in a transparent acrylic sphere the size of a phone booth has implicit risks. Motors can fail, electronics can short, lost fishing nets can entangle. Fortunately, though, the new generation of submarines are built with so many levels of redundancy and fail-safes, the chances of anything bad happening are remote. Of the hundreds of dives Deep Rover and Nadir have made, the crew members here have never experienced a problem.

“There are risks with any research, for sure,” Amon said. “But to me, the rewards so far outweigh any of that. It’s incredible to be out here doing this kind of field research.”

A half hour later, I’m about to experience those rewards for myself. At 10 a.m., I’m standing in socks at the foot of a steel staircase. Below me is Nadir’s open top hatch. Scott is sitting inside the sub guiding me in. “Okay, now, go slow,” he said. With a few torso twists and some sloppy footwork, I manage to wriggle into the passenger seat. Following me is Susan Humphris, a geologist who will be surveying the underwater terrain and biology during the dive.

Scott seals shut Nadir’s hatch, gives the deckhands a thumbs-up, and we slowly creep out along the ship’s aft deck toward open water. Another thumbs-up and a crane lifts us from the deck until we’re swinging a dozen feet in the air like the pendulum of an old clock. I peer between my feet and see the Alucia crowded with crew and researchers. Between them, Klein and Wollermann roll out in Deep Rover. In front of us, there is nothing but horizonless blue ocean.

We lower down into the water, splash at the surface, detach from the guide rope, and float away from the ship. “Okay, all clear,” said Scott into the sonar radio. With a gurgle of bubbles we sink below until there’s nothing but gradients of blue water all around. It’s stunning.

These bands of color aren’t a distortion from the acrylic sphere and we’re not imagining them. What we’re seeing is the spectrum of sunlight being absorbed by water molecules. Long wavelengths of light reds, oranges and yellows are absorbed first, so they disappear near the surface. As we sink lower, past 15 m (50 feet), I notice that my beige pants, my shirt, my skin and notepad have all faded into the same bluish-gray metallic tone.

Deeper still, we sink until there is no blue, no gray, no purple – no light at all. Nothing but black. Scott flicks on Nadir’s lights. We have reached 500 m. At this depth, photosynthesis is no longer possible. The ocean world around us now is almost entirely animal and mineral.

“Affirmative, Deep Rover, I see you,” said Scott. In the distance, two pinprick white lights emerge from the blackness. It’s Deep Rover. Even though we are only a hundred or so meters away, Wollermann and Klein will need to wait about four seconds before they receive our transmission. Radio waves can’t transmit through water, so the submarines must communicate through sound waves via a sonar system. Each audio transmission we send travels through the water column all the way up to the Alucia where it is then sent back down to Deep Rover.

About 10 seconds after our transmission, we hear an echoey squawk layered in reverb and noise come through Nadir’s speaker. Scott tells me that understanding sonar transmission takes a trained ear and time, the same kind of listening skills dentists use to translate the open-mouth garble of patients.

The sub pilots exchange a few more commands, then we turn to face Deep Rover head-on. While moving a machine around in the terrestrial world may take a few seconds, down here in the deep ocean even simple maneuvers can take minutes due to the water’s resistance and the limited power of the subs, which crawl at a maximum of about 4 knots (4.6 miles per hour).

The syrupy slowness of our movements combined with the rising humidity inside the pressure hull gives the whole scene a dreamlike, meditative quality. After a while, it feels as though our bodies are slowing down too – seconds turn to minutes, minutes turn to hours.

“Carbonate, very interesting,” said Humphris. She’s been recording our every move like a stats fan at a baseball game ever since we hit the seafloor. The presence of carbonate rocks, Humphris says, is an indication that there was likely, or still is, hydrothermal activity in the area. “Promising, for sure,” she said, penciling another acronym onto the sheet.

Meanwhile, in front of us, Klein has extended a mechanical arm from Deep Rover and is attempting to grab some of what looks like carbonate rocks on the seafloor. Operating a mechanical arm is difficult, and the work is slow going.

Scott takes the opportunity to hand out our lunch boxes. We munch on chips and cheer when Klein manages to coerce a rock into the sample bucket; and we boo when samples slip through the mechanical fingers and are swallowed by the blackness below.

This goes on for an hour or two. It occurs to me how bizarre the pursuit of deep life has become. Here we are in a hollowed out plastic marble, sitting in perfect comfort 500 meters below the surface of the Atlantic Ocean, nibbling on Flamin’ Hot Cheetos and dark chocolate Kit Kats, watching the little steel fingers of a robotic arm probe holes into million-year-old microscopic bones. If we told our ancestors a hundred years ago we’d be doing this, nobody would have ever believed us. As I sit here, experiencing this, I’m not even sure I believe it myself.

Scott takes another handful of Cheetos, grabs the control stick and leans back. The oxygen gauge in the sub is reading about 20 percent. Although we have dozens of hours of reserves, it’s always best to play it safe.

“Okay, that’s it,” said Scott into the receiver. “Heading up.” He flicks a switch, the electric motors hum, and we begin to rise upward. Inky blackness bleeds to deep purple which bleeds to neon blue and finally, at the surface, blinding, glorious yellow sunlight.

“Easy, huh?” said Scott, squinting in the magnified sunlight. I look at my phone. Five hours have passed since we left the surface. I nod to Scott, “Easy.” My only regret is it went by so fast that I didn’t even know what happened.

That evening Schubotz is in a makeshift laboratory jostling between cases of sparkling water, condiments and cases of Brazilian beer. She is organizing test tubes on a cutting board covered with what looks like black dust. Over the past few days, Schubotz has been soaking the samples in hydrogen, carbon dioxide and methane, hoping to spark some kind of reaction. She’s also been trying to “feed” them heavy carbon. If there are microbes on the rocks, they’ll likely consume the carbon and become measurably heavier.

Cells in the human body, such as those in the small intestine, can replicate, or “turn over,” in just a matter of days. The turnover of some deep microbes, however, can take weeks to months to years or even decades. “It’s a lot of detective work, which makes it so fascinating,” she said. “You’re dealing with just such a crazy dimension.”

Schubotz and the rest of the scientific team are certain that hydrothermal activity occurred here at Saint Peter and Saint Paul Archipelago, but suspect that the activity occurring now, if it’s occurring, is likely lower-temperature, subtler and slower than at most other vent systems.

Over the next several months, Schubotz will take the samples back to the laboratory in Bremen, Germany, and try to determine if the heavy carbon has been consumed, which will prove that microorganisms are active – that the rocks here are harboring hydrothermal life. “Only time will tell,” she said, shooting a smile.

On our last day here, we finally have the opportunity to set foot on dry land. Not as if there’s much of it and not as if there’s much to see. Nothing really grows on Saint Peter and Saint Paul Archipelago; there is no sand, no shade. The only people who live here are a crew of mostly-shirtless Brazilian Navy sailors who rotate every fortnight. As we approach in a smaller tender boat, the sailors wave us in. We tie up, climb a rusty ladder over a sheer wall of rock and gather on an elevated wooden boardwalk.

Charles Darwin came to these little islets in 1832 while on a five-year cruise around the world aboard the HMS Beagle. Upon landing, he described being surrounded by two species of pelicans and gulls, so “gentle and stupid” they remained perfectly calm, and perfectly still in his presence, surely because they had never seen humans before.

Those days are, sadly, gone. As the crew and I scurry past, the few hundred brown boobies (Sula leucogaster) that call the archipelago their home lunge at our ankles, shins, and knees. We manage to escape them and enter the porch of the plywood Brazilian Navy bunkhouse. We exchange a few bom dias, sip some water, and take a seat. The tour of Saint Peter and Saint Paul Archipelago is over.

While the rest of our group heads out for a swim, I excuse myself, hop off the walkway to explore the unpaved crevices, and discover a little secluded cove frothed in spindrift. From this vantage there are no crap-covered satellite disks, broken outhouses, bunkhouses or plastic bottles. No sign of human presence, just bare mantle rock surrounded by blue ocean that goes on forever.

This is how these rocks looked when they were first pushed up from the seafloor, when they cracked and fissured and coupled with the seawater to give birth to primitive life.

And here we are, a few billions of years later, back together again, the descendants of that rock and water, staring at each other, still piecing together our family tree, trying to find a way back home.

This article originally appeared on bioGraphic under the headline Life on the Rocks