The marine biologist Jay Barlow likes to say that he went looking for the last of the Ice Age mastodons and instead bumped into a unicorn. It’s a land-based metaphor to help us, a landlubbing species, make sense of what he witnessed late last year, though in fact the mystery unfolded entirely out of sight of land.

In 2014, a team of scientists described acoustic recordings taken far off the coast of California that they suspected were the clicks and buzzes of the Perrin’s beaked whale, the mastodon in Barlow’s metaphor. Though they include 23 known species ranging in size from the pygmy beaked whale, which is about as long as a small hatchback, to the Baird’s beaked whale, which can be nearly the scale of a cargo trailer, beaked whales as a group have remained overlooked cousins of the dolphins and great whales to the present day. Perrin’s beaked whales were among the most obscure of the obscure. Known only from a few carcasses washed ashore in California, they had never been documented alive in the wild.

Four years after those first recordings, acoustic data collected during a National Oceanic and Atmospheric Administration survey captured the same noise pattern. This time it was concentrated around a nameless, undersea ridgetop in the open Pacific Ocean—the middle of nowhere, really—located about 350 kilometers south of the United States–Mexico border. “It was really abundant there,” Barlow, who specializes in marine mammals, told me. “We thought, well, this is good news, maybe we found a spot where the density of the Perrin’s beaked whale is high enough that we might actually have a chance to be the first people to see them.”

It took awhile to put together an expedition during a pandemic year. But on November 15, 2020, a search team co-led by Barlow, the U.S. Navy marine researcher Elizabeth Henderson, and Gustavo Cárdenas Hinojosa, a scientist with the agency responsible for protected areas in Mexico, set sail from a port on the Baja Peninsula. They were aboard a sailboat provided and crewed by the Sea Shepherd Conservation Society as part of a research campaign called Operation Divina Guadalupe—a reference to the image of the Virgin Mary that many Mexicans turn to when they need a miracle.

Active surveying for whales began on the second day at sea; the team saw only a few dolphins. By first light on the third day, the boat was floating nearly a kilometer above the flanks of the unnamed submarine peak where NOAA’s recordings had been made. As a general rule, beaked whales are hard to spot: They slip to the surface rather than surge to it, release no “Thar she blows” puff of exhaled mist, and can easily be hidden by waves kicked up from a gentle breeze. This day, however, the sea was so calm that, looking over the rails of the boat, the crew could see their reflections. “Beaked-whale weather,” Barlow said.

The search started at 6 a.m., with the sun still below the horizon. Eight minutes later, three beaked whales surfaced so close that the scientists didn’t even need to lift their binoculars to see them.

If beaked whales can be hard to see, they are even more difficult to identify. Most look like oversize, thuggish dolphins: They’re often described as cigar shaped, but if so, the cigar is a perfecto, thick through the middle and tapering to the tip and tail. They mainly come in muted tones of gray-brown to blue, often with stripes or polka dots. Neither pattern is as charming as it sounds. The stripes are thought to be scars from underwater battles between males. The polka dots are scars left by the cookiecutter shark, a thalassophobia-inducing creature with jaws designed to remove round plugs of flesh. They sometimes punch permanent holes through beaked whales’ fins.

Telling beaked-whale species apart often comes down to the teeth, a task complicated by the fact that, for the most part, beaked whales are toothless. In nearly all cases, only the males have visible teeth, and usually just one on each side of the lower jaw. The position of these teeth is often distinctive, and their form can be, too: Some resemble ginkgo leaves, others the oblong flensing spades used by 19th-century whalers. The tusks of the strap-toothed whale grow up and across the snout, like a bone ribbon that ties the mouth nearly shut. This apparently causes no problems, because beaked whales—keeping it weird—neither bite nor chew their food. They are suction feeders, drinking in their meals rather than eating them, and they’re also teuthivorous, meaning they primarily eat squid. To do so through a narrower mouth opening only makes the process akin to slurping up noodle soup without cutlery.

When the beaked whales surfaced near the Sea Shepherd boat, the scientists scrambled to make observations, take photographs, and deploy acoustic-recording buoys: Beaked whales are notoriously skittish. Yet these whales lingered for more than an hour, seemingly as curious about their visitors as the visitors were about them. A diver even managed to record some underwater video. Ticking through observations of the whales’ size, coloration, and head shape, the team was soon confident that they weren’t looking at any of the area’s better-known species. “We assumed that these would be Perrin’s beaked whale,” Barlow said. They had found the last mastodons, deep in their hidden valley.

A photograph taken by Henderson seemed to clinch the case. Male Perrin’s beaked whales have their teeth near the tip of the beak, or rostrum, and the image appeared to show just that. On closer inspection, however, the “teeth” turned out to be glints of sunshine. When other photos seemed to show teeth near the midpoint of the jaw, the hope that they had seen Perrin’s beaked whales began to slip away.

“I didn’t want to believe it at the time,” Barlow said. They began to compare their images and audio to descriptions of every other species of beaked whale, trying to make a match. At last, another possibility dawned: that what they had witnessed was not the never-before-seen-alive Perrin’s beaked whale, but a new species entirely. In other words, the metaphorical unicorn: a kind of beaked whale—in this case, an animal twice the size of a bottlenose dolphin and as heavy as a plow-pulling horse—that had somehow gone unnoticed, never known to be seen dead or alive by human eyes. “We were all giddy,” Henderson told me. “There might have been some dancing.”

Back onshore, the news was welcomed as a sign that, just possibly, the human race has not yet left its gaudy thumbprint everywhere. The excitement was heightened by the fact that it was the second year in a row that such a “unicorn” had been reported: In 2019, scientists announced that what had always been considered a smaller, darker variety of the Baird’s beaked whale—one of the best known of the little-known family of beaked whales—was in fact a different species hiding in its cousin’s shadow. That such large animals could remain out of sight on a planet teeming with people and our panopticon technologies into the third decade of the 21st century seemed almost beyond belief.

Whales as a whole are apostates. Life on our planet began in the water and moved onto the land, an evolution that is often represented—in graphics that show fish growing legs and ending up as human beings—as progress. Yet the cetaceans, that grouping of creatures that includes whales, dolphins, and porpoises, reversed the trend. They came ashore, took a look around—and returned to the sea, turning their backs on what would become the human dominion.

Beaked whales were the most emphatic about it. If you have never heard of beaked whales before now, rest assured you are not alone. Other cetaceans appear in the Bible, were carved into rock more than 5,000 years ago in Norway, turn up on fourth-century bas-reliefs. I found a single possible reference to a beaked whale in early art: a playful glass sculpture from Greece that depicts a cetacean with a long, birdlike beak but without the tall fin of a dolphin. Coastal cultures have always known about beaked whales, from animals stranded onshore or glimpsed at sea, but such events were probably as uncommon in antiquity as they are today. The most consistent impression the whales have left on humans is that their flesh and blubber make for dubious eating; a 13th-century Icelandic text gives fair warning that the rendered fat “runs right through” not only humans “or any other animal,” but even vessels made of wood or horn.

In 1823, the French zoologist Georges Cuvier examined the skull of an unknown sea creature and concluded that it was the fossilized remains of an extinct cetacean; the Cuvier’s beaked whale is now believed to be the most widespread of the beaked whales, ranging nearly throughout the world’s oceans. The British scientist William Flower, one of the first people who might fairly be described as anything like a beaked-whale expert, had the following to say in 1872: “Their very presence in the ocean seems to pass unnoticed and unsuspected by voyagers, and even by those whose special occupation is the pursuit and capture of various better known and more abundant cetaceans.” In other words, beaked whales have, with few exceptions, remained at such a remove from human existence that we have never made a habit of hunting and killing them.

Much of our knowledge of beaked whales is still emerging from a vast memento mori of bones and tissues gathered from stranded specimens and housed in the world’s museums. Chris Stinson, a curatorial assistant at the Beaty Biodiversity Museum in Vancouver, is a beaked-whale aficionado (“I just like things that nobody knows anything about,” he told me) and once spent 12 days on a whale survey off Canada’s west coast, during which he logged just about every kind of whale out there—except beaked whales. The closest he has come to an encounter with them is still the museum’s collection of skeletal remains.

He pulled out 10 sets of bones for me. Lifting a Hubbs’ beaked whale skull, it was humbling to think that I could dedicate the rest of my life to seeing the species alive in the wild, and would probably fail. (Humankind’s only truly close encounter with living Hubbs’ whales involved two stranded juveniles who were placed in captivity in a California oceanarium 30 years ago; both died in less than a month.) The skull was an awkward armload. Bizarrely, its size, shape, and long, narrow bill brought to mind the head of Big Bird from Sesame Street, but with none of bird-bone’s lightness: It had heft and density. Without Stinson’s help, I would never have guessed where the eye socket was, and would not have been sure which side was up or down.

“You can’t even tell it’s a skull, really,” Stinson said. “Back in 1997, when I first moved to the West Coast, if I had seen one of these washed up on a beach, I would have thought it was some kind of crazy alien.”

Ironically for animals so little known to us, many beaked whales are named after people—white men, to be exact. (One exception is Deraniyagala’s beaked whale, identified in 1963 from a carcass examined by Paul Deraniyagala, director of the national museums of what is now Sri Lanka.) Most of these men likely never saw a beaked whale alive. The first field studies didn’t begin until the late 1980s, when Hal Whitehead of Dalhousie University in Nova Scotia began to make excursions to the Gully, an underwater canyon 200 kilometers off Canada’s east coast, to research a species of beaked whale called the northern bottlenose whale.

The people who first studied beaked whales in the wild tended to share a similar experience: When they first set out, they were warned that their ambitions were hopeless, because the whales are so rarely seen. Diane Claridge is one such pioneer, having studied beaked whales in the Bahamas since 1991. She told me that even now, having discovered that the Bahamas have long-term, largely site-specific populations of Blainville’s beaked whales, and with three decades of accumulated knowledge about how and where to find them, she still only locates them on about 80 percent of field days—and doesn’t even bother to go looking if the ocean isn’t calm. The sightings often come after hours of searching, and then might involve only brief observations before the animals dive.

“Our notes are like, ‘Up. Down. Up. Down,’” Claridge said.

“Our notes say, ‘Went to this location, searched for an hour. Went to this location, searched for an hour,’” added Charlotte Dunn, her colleague at the Bahamas Marine Mammal Research Organization.

“There’s not many people in the world who would want our job,” Claridge said.

Today, thanks to a handful of dedicated researchers around the globe, four species of beaked whale are relatively well studied: the northern bottlenose whale, Baird’s beaked whale, Cuvier’s beaked whale, and Blainville’s beaked whale. That leaves 19 species of beaked whales—again, creatures of a size that would seem tricky to lose track of—that are somewhere between mysteries and total enigmas. If the species spotted by Operation Divina Guadalupe off Baja last year is confirmed to be a new one, the tally will rise to 20.

When the first handbook dedicated exclusively to beaked whales was finally published in 2017, the authors declared them “the least known of all the large animals in the world.” We know more about certain dinosaurs than some living beaked whales. Yet they are out there right now, perfectly familiar to themselves, perhaps rolling at the surface in a gale, or, in the words of one scientist, “singing their clicks and whistles into the abyss.” They have not needed to come from outer space in order to be otherworldly. They’ve only needed a parallel universe: the life aquatic of the deep sea.

Beaked whales are diving whales, or else, as some now say, they are surfacing whales. It’s a matter of emphasis, of orientation. To call them diving whales is to say that they live at the surface and visit the depths. To call them surfacing whales turns the formula around.

There are few signs that beaked whales take pleasure in time spent at the interface between water and air. When at or even near the surface, they are usually dead silent. They don’t hang around for long, either, often only a minute or two before disappearing. Night and day, probably year-round, they are either making deep dives or preparing to do so, a metronomic pattern that suggests they prefer to spend their time in the lightless waters far below, but regrettably need to breathe air to do so.

“They’re just on this really tight cycle,” Dunn said. “It’s like they don’t have any time to do anything else. Work, sleep; work, sleep.”

Dives of 1,500 meters are ordinary. The deepest on official record is nearly 3,000 meters, but only because a plunge measured at 3,568 meters was discounted due to the fact that the whale’s satellite tag had only been pressure tested to three kilometers of depth. Then there’s the fact that submersibles have photographed large gouges in the seafloor that resemble marks made elsewhere by beaked whales, but they run as deep as 4,258 meters below the surface—two and a half miles down. “I don’t know what to think about this, as it’s super deep and seems insane,” said Nicola Quick, who has studied beaked-whale diving as a research scientist with Duke University’s marine lab.

Yet it is in the deep-water “midnight zone” that beaked whales seem to come to life. There, safe from predators like sharks and killer whales, in cold darkness lit only occasionally by the ghostly glow of luminescent sea creatures, they burst into the sounds they use to echolocate their prey. Somewhere beneath the waves, too, is where the behaviors human eyes have never seen—from males slashing each other with their tusks in battles for dominance to couples mating to the basic act of feeding—presumably take place. The beaked whales might even nap as they tumble into the abyss—scientists have no clear sense, really, of how they otherwise fit enough rest into their 24-hour diving cycle.

“They do things they are not supposed to be able to,” says Andreas Fahlman, a research scientist with the Fundación Oceanogràfic in Valencia, Spain. The essence of how beaked whales have escaped our attention is not how deep they dive, but how long they stay down there. People have forever been fascinated by animals that live in water but, like us, must hold their breath when they’re under it. In an early exploration of such creatures’ limits, the American physiologist Laurence Irving once held a muskrat under water for 12 minutes, only to watch it dive again the moment he let it go. (He gave up on a beaver after just six minutes, when it started thrashing.) At the time, Irving was aware of whalers’ reports that northern bottlenose whales could linger underwater for two hours. Such claims sounded apocryphal.

The longest dive now known for a beaked whale—and there’s little reason to think that the record will hold—was performed by a satellite-tagged Cuvier’s beaked whale in 2017. It stayed beneath the surface for three hours and 42 minutes. This is the equivalent of getting back to the office after your lunch break, then holding your breath until the workday’s nearly done. The current breath-holding record for a human is just over 24 minutes, accomplished while floating motionless after hyperventilating pure oxygen. Beaked whales can go without breathing while diving downward for half an hour or more, hunting squid and deep-sea fish under crushing hydrostatic pressure, then swimming back to the surface.

Beaked whales’ astonishing undersea journeys are explained in part by what has been described as “extreme morphology,” or the unusual way their bodies are structured. Relative to us and even to other cetaceans, beaked whales have a lot of muscle and blood for their size, and both contain extraordinarily high concentrations of proteins that can store oxygen. To conserve that oxygen on their dives, the whales likely shut down all but the most essential bodily functions. “They are probably not thinking hard about math and physics problems,” Fahlman told me. “They’re probably limiting what they’re doing and focusing on certain things.

Returning to the surface presents beaked whales with their greatest challenge. Like scuba divers, they can get “the bends,” also known as decompression sickness. As they descend, nitrogen from the air in their lungs dissolves into their blood and tissues under the increasing pressure of the deepening water. When they make their way back to the air-breathing world, that nitrogen can come out of solution—picture what happens to soda water when you crack the cap of the bottle, releasing the pressure within—as bubbles that can damage organs and block blood vessels.

To avoid this, Fahlman said, the whales appear to use three main strategies. First, as a beaked whale begins its descent, most parts of its lungs completely collapse, preventing those areas from exchanging nitrogen into the blood. As current theory holds, the whale might then rely on a highly unusual capacity: It diverts its blood so nearly all of it circulates only past the collapsed regions of the lungs. Finally, the whale returns to the surface while gradually directing circulation toward open areas of the lungs. That way, nitrogen that did enter the bloodstream can be exchanged back to the lungs as a gas and exhaled through the animal’s blowhole once it reaches the air-breathing world. It then fully reopens the lungs and begins stowing away oxygen for the next dive.

Researchers have described these capacities as “conditioned control,” meaning they are probably grounded in experience, the way marathon runners learn to pace themselves over long distances. Embedded in that careful wording is the possibility that the whales make at least some of these bodily shifts through conscious effort. “Most of the evidence is pointing to the fact that they have a much greater capacity for varying the heart rate, and they’re varying the heart rate based on planning what they’re going to do,” Fahlman said. “Personally, I think they can do whatever they want with their heart rate.” If so, it would be as though you or I could dial down our hearts from 80 beats a minute to 30, almost literally in a heartbeat. It would be as though we could, at will, pop in and out between complete wakefulness and a state close to hibernation, or stop the clock anywhere in between.

Does all of this mean that science can fully explain a three-hour-plus-long dive? “No,” said Fahlman, laughing. “They are so far beyond what they should be able to do that it is incredible.”

For now, no one can say for sure whether Operation Divina Guadalupe witnessed a new beaked-whale species off the coast of Mexico last November. There is only one way to put all doubt to rest, and that is genetic evidence. The scientists, having leaped into a small boat during the encounter, managed to collect seawater samples from the whales’ wake as they dove. The samples may contain high-quality DNA in, say, flakes of the animals’ skin; if so, the whales’ genes either will or will not match the data bank of known beaked-whale species. The samples are now in a Seattle lab, with results expected perhaps as soon as the end of April.

An extraordinary chance event provides another possible line of evidence. On February 22, an as-yet-unidentified beaked whale stranded and died on a beach near San Felipe, a town in the Gulf of California, that narrow stretch of the Pacific that runs up the opposite side of the Baja Peninsula from where Operation Divina Guadalupe spotted their mystery whale. The two encounters were separated by more than 2,000 kilometers of water, but on an oceanic scale took place in roughly the same neighborhood. The San Felipe whale also resembled the females seen by Barlow, Henderson, and their colleagues, though female beaked whales of different species can be notoriously difficult to tell apart. Tissue samples were collected from the stranded whale, and once COVID-19 rules permit it, genetic testing will occur at labs in both Mexico and the U.S. If the San Felipe whale proves to be a known species far outside its known range, then that is more likely true of Operation Divina Guadalupe’s sighting as well. If the San Felipe whale turns out to be a species new to science, it ups the odds that the other Baja whales are that same new species, too. Or not. When it comes to beaked whales, it’s not beyond belief that two new species, or a new species plus a previously unknown population of a known species, could be discovered within a matter of months.

Ultimately, there is nothing for it but to find the Baja whales again. Doing so is far from guaranteed: The designated search area for the original expedition was a patch of ocean the size of Maine, and after the original “unicorn” encounter on day three of the two-week trip, they saw no other beaked whales of any kind. If they do succeed in finding the whales a second time, the researchers will try to shoot one with a crossbow bolt designed to extract a small core of skin and blubber for genetic testing.

Leave them alone, you might be thinking. It is probable—very likely, in fact—that many if not most beaked whales are unaware of the scale of human civilization. They have never seen our crowded beaches, our busy ports, the lights of our cities that trail across the waves like a thousand moons. When the poet C. H. Sisson wrote, “Think nothing of the whale: you may be sure / He thinks nothing of you,” he was speaking most truthfully of beaked whales.

Already, much of what we know about the beaked-whale family is the result of unfortunate collisions between us and them. The first detailed scientific description of any beaked whale came after a northern bottlenose whale wandered up the Thames River and was killed near London Bridge in 1783; the anatomist John Hunter dissected it and preserved its heart. The first reports of beaked whales’ diving and breath-holding abilities came from whalers awestruck by the animals’ power to pull fathoms of line straight down when harpooned. Our knowledge of their physiology advanced in 1885, when the British professor William Turner came into possession of a Sowerby’s beaked whale that two Shetland Islanders had driven ashore by stoning before chopping off its tail with a clasp knife and a peat-cutting shovel. It left behind an orphaned calf.

The pattern has continued. The ginkgo-toothed beaked whale was first identified in 1958, after some boys in Japan beat one to death with baseball bats when it strayed into shallow water. Pygmy beaked whales—whose existence wasn’t known until 1991—came abruptly into our awareness when they began to turn up, drowned to death, in the drift nets of the shark fishery. Dead beaked whales, including species rarely if ever seen alive at sea, have washed up with bellies full of garbage, propeller gashes from ship strikes, and chemical-pollutant levels above the toxicity threshold. Much of the reason that new and rarely seen beaked-whale species have seemed to make their debut in the 21st century comes down to a surge of research that followed the deaths of at least six beaked whales in the Bahamas in March 2000, an event that left little doubt that the use of Navy sonar could cause mass strandings. The best explanation so far for why this happens is that sonar spooks the diving whales badly enough to disrupt the delicate equilibrium they maintain to descend into the midnight zone and somehow come back alive; whales stranded after sonar events have been found with “bubble-associated lesions” in vital organs and hemorrhaging in their ears and brains. Surveying the state of our awareness of beaked whales as a whole in 2017, the biologists Richard Ellis and James Mead wrote, “We still know very little about where they live—it might be said that we know more about where they die.”

It’s hard to say whether remoteness from our human ambitions is sheltering beaked whales or endangering them, Bob Pitman told me. Nearly 50 years ago, Pitman was an avid birdwatcher who turned to studying whales because of the greater interest in their conservation. (“Mammals pay the bills,” he said.) The birder’s fondness for tick lists never left him, though, and he ultimately decided that he would try to see every species of cetacean alive on Earth. At times he has spent eight to 10 months at sea each year, not even bothering to rent a home ashore.

Pitman, currently a marine ecologist with Oregon State University, has now probably seen more species of beaked whale than anyone else in human history. In 1994, for example, he once saw Hubbs’ beaked whales four times in a single day; they are the only confirmed sightings on record of the species at sea. Another time, on one of dozens of trips he has made to Antarctica, he glimpsed a small group of Shepherd’s beaked whales—a species that was first observed alive in the wild from a helicopter in 1985, near the aptly named Inaccessible Island in the South Atlantic. For that species, Pitman’s sighting is one of what remains a very short roster.

Today, he has eight species of cetacean left to go to complete his tick list. One is an endangered dolphin that lives in the Indus River; he needs to book a trip to Pakistan to see it. The other seven are all beaked whales. Pitman knows of only a somewhat dependable place to find one of them: Berardius minimus, the relative of the Baird’s beaked whale that was finally recognized as a separate species in 2019, is seen a few times a year by whale watchers off northern Japan. After that come the ginkgo-toothed beaked whale, Perrin’s beaked whale, Deraniyagala’s beaked whale, Andrews’ beaked whale, Hector’s beaked whale, and the spade-toothed beaked whale. “I don’t think any of them have been identified alive in the wild,” Pitman said. “You just got to go out in the middle of nowhere and look for them.”

Pitman had hoped to join the fateful trip that spotted the “unicorn” whale off Baja last November, but COVID-19 restrictions made it too difficult. When the next expedition is mounted—likely later this year—he plans to be on it. It could potentially save him having to add yet another unseen beaked whale to his list. “They keep moving the goalposts,” Pitman said.

Far heavier on his mind than the possibility that more beaked whales will be discovered (he thinks they will be) is the cetacean that got away. In 2006, he made a research trip to China to look for the baiji, also known as the Yangtze River dolphin. He and his colleagues searched the legendary river’s entire 1,700-kilometer main channel, twice. They counted nearly 20,000 large shipping vessels and more than a thousand fishing boats, but no river dolphins. At the end of their quest, they declared that the species was likely extinct, a conclusion now widely supported. For all the terrible harm that humans have done to cetaceans, drastically reducing their abundance and range, the baiji was the first of them that we ever completely extinguished. It happened in the 21st century.

Mystery cuts both ways. There is beauty in the idea that beaked whales are out there, truly wild, a corrective to our inflated sense that everything revolves around our own big-brained, thick-skulled species. To seek them, though, is a hopeful act: It adds rather than subtracts. At the least, we might need to encounter the whales to have any chance at leaving them alone. As much as we are finding some beaked whales for the first time, we could be losing others without ever having known them.