It is, then, a purely submarine aspect of our biology. Humans exposed to high pressure on land fail to flip the Master Switch. Human divers survive at theoretically fatal pressures because of a reflexive retreat of blood from the extremities to the vital organs, which keeps the brain and heart flush with oxygen and the lungs engorged with enough blood to prevent collapse. Nestor meets researchers who freedive in order to attach satellite transmitters to sharks by hand, and freediving amid marine life, Nestor writes, is “the most direct and intimate way to connect with the ocean.” Nestor himself decides to learn to freedive (not competitively), and via that process unveils startling facets of human physiology, most prominently the life-preserving reflexes known as the Master Switch of Life. (In November, The New York Times ignited a public discussion of journalistic ethics with a photo of bulging-eyed Nicholas Mevoli moments after he emerged from a freedive record attempt and just before he blacked out and died.) When practiced outside the structure of competition and the reckless chasing of depth records, however, freediving can be practical, even beautiful. At first intrigued, Nestor quickly becomes disgusted as one diver after another surfaces with blood pouring from their noses, or dragged unconscious by rescue divers or in cardiac arrest. Top divers submerge for more than three minutes and reach depths below 300 feet, where pressure causes human lungs to “shrink to the size of two baseballs,” Nestor writes. Divers hold their breath and see how low they can go without suffering grievous harm. The underwater travelogue begins near the ocean’s surface, where Nestor’s tour guides are competitors at the world freediving championship.Ĭompetitive freediving, Nestor quickly makes clear, is a ridiculous sport. The ocean’s opacity makes James Nestor’s mission in “Deep: Freediving, Renegade Science, and What the Ocean Tells Us About Ourselves” particularly ambitious: to see the sea, from surface eddies to fathomless trenches. Had Flight 370 crashed into the moon or Mars, we would have found it by now, because we have better maps of those desiccated surfaces than of our own planet.
The difficulty of finding a Boeing 777 can serve as a symbol of how little we know about the portion of our planet that lies beneath the surface of the ocean. Trouble is, most of that sliver - like 71 percent of Earth’s surface - is covered by water. How, in this age of surveillance, can we lose a 210-foot airplane? With its known initial flight path and fuel load, investigators can restrict the last possible position of Malaysia Airlines Flight 370 to a sliver of the globe.
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