Our guide, Castor, is serious when he tells us, "No camera. No flashlight. No cigarette." It's 10 o'clock at night, and we've been stumbling along behind him and his wife, Maria, on the beach in complete darkness for half an hour, hoping that every shadowy form is a giant green sea turtle that has emerged from the Caribbean to lay her eggs on Tortuguero Beach.
My husband and I have traveled from the central highlands of Costa Rica - three buses, a taxi, and a five-hour boat ride - to the western Caribbean coast, just miles from Nicaragua, hoping to witness this event in late October at the end of the nesting season. Thunder rumbles behind us offshore. A crack of lightning crosses the moonless sky. Ominous raindrops threaten to end the whole expedition, and I wonder how the baby turtles ever find their way to the sparkle of the sea on a night such as this.
We traipse behind Castor and Maria in dutiful silence, contemplating the impact we could have on a turtle's nesting decision. Although they can't hear well, green sea turtles have a powerful sense of smell. Strong odors and lights can disturb them, and if the female feels threatened, she'll likely return to the sea to abort all 100 to 120 of her eggs - a huge sacrifice for an endangered creature.
Earlier that day we had read up on threats to the turtles - toxic waste, plastic bags, and fishing hooks among other things - at the Caribbean Conservation Corporation information center in the village of Tortuguero. These threats apply, however, only if the baby turtles even make it to the sea in the first place.
Behind Tortuguero beach is a thick jungle and a national park that are inhabited by 57 species of amphibians, 111 species of reptiles, 60 species of mammals, and more than 300 species of birds. While the Caribbean Conservation Corporation has helped curb the human appetite for turtle meat and eggs - Tortuguero means "turtle catcher" in Spanish - natural predators remain hungry. Hundreds of broken eggs and shells litter the beach, commingling with debris such as dead coconuts, driftwood logs, even garbage.
Yet this vast area also produces most of the green sea turtles of the Caribbean.
I had imagined groups of tourists prowling around the beach, all of us hovering in a huge, gawking circle over a nesting turtle, but, surprisingly, we're the only ones. Castor explains that some guides take people out at 8 p.m., but we're less likely to see anything at that hour.
We stumble farther, past the end of Tortuguero village. Night sounds kick in, mysterious calls of unknown birds and insects, followed by profound silence. Then Castor stops suddenly, our small group coming to a clumsy halt behind him. With his low-beam flashlight, he draws our eyes down to the sand, churned as though a miniature tractor had driven up onto the beach and headed straight inland.
Castor slips away, follows the trail, and returns. "She is there," he reports, "making her nest now. We'll wait for her to finish and then we will see her lay the eggs."
Castor lowers his voice, stoops over with his hands on his knees, and explains what the female turtle is doing: She's using her body like a giant power drill, turning herself around and around in a circle until the top of her shell is nearly even with the sand. Using her powerful, leathery flippers she scoops sand out around her, burrowing deeper. Employing her back flippers, she then reaches beneath herself to dig a neat, deep hole for the hundred or more eggs she'll lay this evening. In two weeks, she'll come back to this beach and lay some more.
In hushed tones we shower Castor with questions. How long do the eggs need to hatch? Sixty days. How long do green sea turtles live? A hundred years or more. How much do they weigh? They average 300 pounds. Why this beach? The conditions are just right, and the turtles nest on the same beach on which they were born.
From Tortuguero, the hatchlings may travel the Caribbean Sea for decades. Once the females mature at 20 to 30 years old, they'll return here to lay their eggs every few years.
Then Castor is off again. We sit silently on a big piece of driftwood, waiting patiently like family members outside the birthing room. Some minutes later, we get the message we've been waiting for: "It's time, she is ready." In the dark we move up the beach, wondering where she is exactly, hesitantly stepping as though we might trip over her.
"Come, come close, have a look," Castor says, and we gravitate toward the soft red glow of his flashlight. His right hand holds the massive turtle's left rear flipper aside so that the light shines directly into the hole, which is already filling with eggs. The turtle's droopy pointed tail heaves as a soft, slippery egg slides through and plops into the hole, followed by another and another, sometimes two and three in one push, followed by a watery substance.
Watching her tail so intently feels invasive and I wonder out loud if holding her flipper back is among the things guides shouldn't do, but do anyway for the tourists' sake.
"She's in a trance right now," Castor assures me. "She doesn't know we're here."
I gasp in awe as dozens of eggs drop into the earth, recalling that only a sturdy few will survive, and that only 1 to 3 percent of the females who hatch from these eggs will make it back to this beach to lay their own eggs.
The turtle's tail swells one last time, then relaxes, producing nothing. Within minutes her tail flippers begin scraping sand from the walls around her, dragging it over the top of the eggs to build a mound underneath her. Gradually the eggs disappear from sight, and the scraping sound of her flippers subsides.
Castor has slipped away again. He signals us to another spot some distance away. Unbelievably, another nest is hatching at this very moment, dozens of baby turtles desperately flailing their way to the surface, trying to drag themselves up out of the hole and to the sea.
But there's a problem. A huge driftwood log lies embedded in the sand parallel to the sea, obstructing their passage down the beach. As the little turtles scatter from the nest, dazed and looking for the light of the sea, Castor shines his beam toward the water and Maria scoops the newborns up by the handful and places them on the other side of the log.
If we weren't here at this moment, most of them would have wandered aimlessly toward the jungle and death.
Hordes of them scramble from the hole. It's a process that's gone on for 2 million years. I root for every tiny one of them.
Afterward, as we stroll back to the village of Tortuguero, I recall my mixed feelings about the human impact on this environment. Now I'm going home joyous that my presence here helped an entire nest of baby turtles survive the first challenge of their lives.