IF A JAGUAR DECIDED TO slink out of the woods and cause trouble, we wouldn’t stand a chance. There are eight of us — writers and videographers and Instagrammers, all Contiki Storytellers on a trip to document sea turtle conservation efforts in Tortuguero, Costa Rica — but the size of our tribe can’t make up for the fact that on a deserted beach at midnight, without the glow of our mobile devices, we are totally and completely blind.

Cloyd Martinez, the Sea Turtle Conservancy’s buoyant local guide, is impatient to get going. “Your eyes have adjusted, yes?” he shouts into the wind, already too far ahead to hear the answer. “Pura vida! Straight line, follow me! Pura vida!”

Black upon black. A black stretch of sand between black waves and a black thicket of palm trees, hills and gullies punctuated by black seaweed and logs, navigated by humans dressed head to toe in black so as not to disturb the sea turtles’ light sensitivity. Every night on the Caribbean shoreline of Tortuguero National Park, a rotating team of volunteer research assistants from around the world go on long, solitary patrols. They’re looking for turtle tracks. They’re looking for signs that a hawksbill or leatherback, gentle prehistoric giants who have been clambering out of the ocean to lay their eggs on these beaches for 110 million years, has again chosen to entrust the sand with her imperiled cargo. They’re hoping to find the nest before the poachers do, or the rising tide, or the hungry jaguars.

In all those millions of years, sea turtles have held their own against natural predators — hedge a stubborn loggerhead against a shark and don’t be too sure about the spread. Humans, however, are a more daunting opponent. Pollution, nesting ground destruction, and invasive commercial fishing practices wipe out entire populations, and the demand for turtle meat and eggs continues despite widespread bans. Five of the world’s seven species are endangered, some grazing the edge of extinction.

Ecologist Archie Carr brought global attention to the issue in the 1950s and became the founding scientific director of the Sea Turtle Conservancy, now the oldest and most influential organization of its kind. It’s a research powerhouse, but works just as hard at advocacy and education. For people to care about sea turtles, they must know how crucial the animals are to marine and beach ecosystems and how personal actions can make a difference in saving them. Each season, hundreds of tourists visit the Sea Turtle Conservancy and go on night patrols like this one. In June and July, green turtles crawl onto the beach by the dozens.

But it is March, and it is past midnight, and the prospect of spotting a sea turtle is low.

The wind shifts directions. The black takes on shapes and forms. Cloyd stops suddenly and points to a blip of ebony in a sea of midnight, something riding the waves that could either be a leatherback or a log. Our pulse quickens as we stumble over the sand, with each step closer knowing it is indeed a log but feeling the thrill of pursuit nonetheless.

“My father was a poacher,” Cloyd tells us. “Bags and bags of turtle eggs, they would harvest them every season and sell them in the village. But then we started to see how important the turtles are to our way of life. People come to see the turtles. So I decided to protect them. That was two decades ago.” He stops and nods at the faux-leatherback log, the false alarm. “When we were little boys there were so many turtles we used to ride them like horses, all the way back to the sea.”

Two football fields away, there is a phantom flash of red, a signal in the darkness. This time it is no false alarm. A patrol team up the beach is sending a message, a rudimentary laser-pointer Morse code that indicates either a question or a sighting. One flash…two. And then a frantic pulsing that can only mean one thing: A turtle is onshore.

There isn’t time to think about the insanity of sprinting across alien turf without the ability to see. Instead, instinct kicks in. The mind shuts off. Legs propel us over the obstacles and potholes, dodging waves and scrambling for lost footing, but from the lungs up is an eerie calm — a sense of floating. The pounding of waves synchronizes with the pounding of blood in our temples. There is a sudden hyperawareness that the ocean is actually a bright, luminous white, a reflection of the stars overhead. It is intoxicatingly white. It is what attracts newly hatched turtles from the ground to their home, and in that moment of running on instinct, we get a sense of theirs.

A makeshift field camp bathed in infrared light draws near, and in the middle of it is a 850-pound leatherback turtle, midway through the ritual of laying her eggs.

She knows the scientists are there but goes about her business unperturbed, like a mother at a teaching hospital who drifts into the altered state brought on by birthing hormones instead of acknowledging the onlookers around her. Her face is out of view. There is an agreement between the scientists and the turtle: She lets them into the most intimate moment of her life, lets them measure her and tag her and record in their notebooks all the data they need to draw conclusions about the fate of her species, and they stay crouched behind her, always moving out of eyesight so she isn’t tempted to flee to the safety of the waves.

It is with these small acts that they help her. The metal tags they attach to her back flipper contain an ID number that can be tracked across years and migrations. Last season a green turtle that had first been ID’ed in 2000 resurfaced in Tortuguero. Sea Turtle Conservancy tags have turned up in Spain and Portugal, and satellite maps of tagged turtles look like the flight paths of a major airline. Through tagging, data sharing, and satellite tracking, scientists can understand these creatures’ mysterious movements, their improbably long treks propelled by a hard-wired sense of direction aligned to Earth’s magnetic fields. The sea turtle is the ultimate traveler. By instinct it is drawn to a life of freedom across the world’s farthest-reaching currents, and by instinct it will return to the beach where it was born. No matter how far it wanders, it will never forget its home.

Is that why we storytellers, travelers by occupation and design, feel such kinship with the animal nesting six inches in front of us?

She is taking her time. Her back flippers quiver as she deposits her brood, nearly seven dozen jellied ping-pong balls nestled softly in a deep pit, and then heave side to side with elephantine force to conceal the nest. We don’t keep up with her movements fast enough, and a curtain of sand welts our arms and chests. In two months, her hatchlings will emerge and crawl toward light. Only one turtle out of 1,000 will survive to adulthood.

Tonight’s efforts are improving those odds. Since the Sea Turtle Conservancy began its work in Tortuguero, the green turtle population has increased by 500%. Village mindsets evolve as new generations grow up knowing conservation as a way of life. Awareness grows with each visitor, with each reader, with each person who takes action.

As our turtle returns to the waves, she seems to send a message: Go back to your own habitat, to the 4G connections and social media channels that sustain you, and tell my story.

Want to get involved?

Turtle experiences take place in Tortuguero, Costa Rica; Soropta Beach, Panama; Florida, United States; and at various turtle live release events. One- to three-week Eco-Volunteer Adventures on Tortuguero Beach can be booked from March through October.