From the bestselling author of Breath, a "fascinating, informative, exhilarating" voyage from the ocean's surface to its darkest trenches (Wall Street Journal) New York Times Book Review Editors' Choice - An Amazon Best Science Book of 2014 - Scientific American Recommended Read Fascinated by the sport of freediving--in which competitors descend great depths on a single breath--James Nestor embeds with a gang of oceangoing extreme athletes and renegade researchers. He finds whales that communicate with other whales hundreds of miles away, sharks that swim in unerringly straight lines through pitch-black waters, and other strange phenomena. Most illuminating of all, he learns that these abilities are reflected in our own remarkable, and often hidden, potential--including echolocation, directional sense, and the profound bodily changes humans undergo when underwater. Along the way, Nestor unlocks his own freediving skills as he communes with the pioneers who are expanding our definition of what is possible in the natural world, and in ourselves. "A journey well worth taking." --David Epstein, New York Times Book Review "Nestor pulls us below the surface into a world far beyond imagining and opens our eyes to these unseen places." --Dallas Morning News "This is popular science writing at its best." --Christian Science Monitor