In _[DEEP: Freediving, Renegade Science, and What the Ocean Tells us about Ourselves](https://www.amazon.com/Deep-Freediving-Renegade-Science-Ourselves/dp/0547985525)_ James Nestor follows extreme athletes, adventurers, and scientists as they plumb the limits of the ocean's depths and uncover startling discoveries that, in many cases, redefine our understanding of the ocean and ourselves.

Freedivers dive without scuba gear, holding their breath longer than had been thought humanly possible, and thus confirming the legendary feats of Japanese pearl divers. Nestor explains that the human body actually adapts in real time as it reaches depths where we’d expect it to be crushed. For experienced freedivers a “master switch” flips and they are able to handle the pressure and their body automatically ration oxygen to safely extend their time below.

But free diving is only the beginning. Nestor explains how citizen scientist freedivers interact with sperm whales and other sea life in ways that are not possible using other technologies. They can swim within feet of these giant mammals. And the whales amazingly reorient themselves as if to start a conversation. In fact they send clicks (recordings of which Nestor plays onstage) which are used for communication, not geolocation. When you realize how developed the brains of these creatures are, it’s not surprising that they would have something to say. And considering the possibilities of communicating with dolphins and whales is something that Nestor feels strongly about (as he mentioned in [an Ignite Talk he gave for us](https://youtu.be/KrjyevcdNVg) in 02016).

There’s even more in this talk including evidence of how some humans use extra-sensory capabilities that are employed by sharks and whales: magnetic sensitivity and echolocation. In languages that feature cardinal directions rather than relative ones, native speakers always orient themselves correctly in numerous studies--no compass needed. Humans can teach themselves echolocation, and in fact he introduces us to a group of young blind man who uses clicks to enable him to ride a bike through the city and tell one object from another.

Overall Nestor's talk shows us that the wonders of the ocean may be more accessible and relatable than we’d ever imagined them to be.