Deep: Freediving, Renegade Science and What the Ocean Tells Us About Ourselves

by James Nestor

In a world of seven billion people, where every inch of land has been mapped, much of it developed, and too much of it destroyed, the sea remains the final unseen, untouched, and undiscovered wilderness, the planet’s last great frontier.

If you compare the ocean to a human body, the current exploration of the ocean is the equivalent of snapping a photograph of a finger to figure out how our bodies work.

“Scuba diving is like driving a four-by-four through the woods with your windows up, air conditioning on, music blasting,” one freediving researcher told me. “You’re not only removed from the environment, you’re disrupting it. Animals are scared of you. You’re a menace!”

Yes, they were swimming where no human had been before. But this struck me as maddening, like an explorer arriving in previously undiscovered wilderness and focusing only on his GPS coordinates.

Until just sixty years ago, the ama didn’t even wear swim goggles, fearing that this would allow them to see too much and give them an unfair advantage over other creatures in the sea.

And then I begin to see why the ama have kept the ocean to themselves all those centuries, and why they’re apprehensive about sharing their secrets with outsiders, especially men. There I am, the typical male, exploiting the latest technology to find a shortcut into a world I only dimly understand. In some ways, I’m no different than the fishermen on the trawlers sailing out behind us. I am disrupting the balance of the ocean that the ama have spent the last twenty-five hundred years trying to protect.

They also speak their names when they approach humans.

In 1958, during one of his first dolphin experiments, Lilly recorded a click-and-whistle conversation between dolphins and played it back at a slower rate. When he adjusted the frequency and speed of these dolphin sounds in water to match human speech in air, he found the ratio worked out to 4.5:1. This was a remarkable discovery. Sound travels 4.5 times faster in water than in air. The frequency of communication the dolphins were using, if modified to the density of water, Lilly wrote, matched the exact frequency of human speech in air.

But this brings up a question I’ve had ever since we first boarded the boats. Why didn’t they eat us? We’re certainly easy prey. Schnöller believes that, when the whales echolocate our bodies, they perceive that we have hair, big lungs, a large brain — a combination of characteristics they don’t see in the ocean. Perhaps they recognize that we’re fellow mammals, that we have the potential for intelligence. If this theory is correct, then sperm whales are smarter than us in one crucial way: they see the similarities between our two species more readily than we do.

Staring down at the waters of the Puerto Rico Trench — which at its deepest went to nearly 28,700 feet — would be equivalent to standing at the foot of Mount Everest (itself 29,000 feet high).

the farther we descend into the lightless depths of the sea, the closer we get to understanding our origins — our amphibious reflexes, our forgotten senses, where we came from.