The story of humanity’s presence in the deep sea, as told by diver and research biologist Streever (And Soon I Heard a Roaring Wind: A Natural History of Moving Air, 2016, etc.). “I wanted readers to embrace the part of our world that is shrouded by depth,” writes the author at the beginning of this broad survey of “people underwater, about the challenges of getting there, being there, and returning to the surface.” Writing in the conversational style that has marked his previous books, Streever begins with the 1960 descent of the Trieste submersible into the deepest of the ocean floors, the Challenger Deep in the Mariana Trench. It was a remarkable achievement, and the author rides the feat down—here is where scuba tanks implode, here is where the walls of a typical submarine would fail—to the bottom, where the pressure was measured at 16,883 pounds per square inch. This leads into a chapter on the all-consuming role of pressure on diving and its exertion not just on submersibles, but on the human body as well. The author, who lives aboard a cruising sailboat with his wife, offers a solid examination of the behavior of gases as one goes deeper under the waves. There is a smart chapter on breathing as the key to understanding diving, including exhale diving, apnea diving, and free diving. Regarding the last, during the ascent, the pressure in the lungs drops and oxygen in the tissues and blood flows back into the lungs, and the “diver may or may not notice the fading of consciousness.” Although the author discusses the many joys of deep diving both in and out of submersibles, he also emphasizes the perils of going beyond your capabilities. These include everything from working for sustained periods in deep water and relying on exotic gas mixtures to prevent such events as nitrogen narcosis to the fortunes and follies of the first submarines. A buoyant, at times thrilling, account of the deep sea experience, perfect for divers and other lovers of life beneath the waves.