Extreme-sports memoirs don’t interest me much, and James Nestor’s Deep: Freediving, Renegade Science, and What the Ocean Tells Us About Ourselves (Houghton Mifflin Harcourt) would seem to be just that: a lengthy investigation of the sport known as free diving, an extreme activity if ever there was one, in which humans dive unprotected and unassisted to remarkable underwater depths and (mostly) come back to tell us about it. But this book is much more than that . . . much deeper. Woven around hair-raising tales of this sport’s elite and their psychology are the author’s fascinating ruminations on the physiology of humans in the ocean and our ancestral relationship to creatures of the sea; a capsule history of research into cetacean intelligence; and a primer on changes in flora and especially fauna under the crushing pressures at the bottom of the world’s oceans. There is orders of magnitude more cubic real estate down there than what we presently inhabit up here on the surface, most of it in perpetual pitch-blackness and teeming with life. We know arguably less about these realms than we do about the surfaces of distant planets. One comes away from this book with a powerful sense of the limits we place on our own understanding of what we are and where we live; as the author says, Earth looks blue from space, but in reality most of it is black.
Carroll Dunham is an artist based in New York.