Inside of these clicks is encoded information... a secret language... - James Nestor

[T]here is no oxygen tank at the end of the rope, and if there had been... their lungs would have exploded... and their blood would have bubbled with nitrogen before they reached the surface. ...The human body can withstand the pressures of a fast three-hundred-foot... ascent only in its natural state.
Some humans handle it better than others.

These more philosophical freedivers get... the same look one sees in the eyes of Buddhist monks or emergency room patients who have died and then been resuscitated... who have made it over to the other side.

At three hundred feet... pressure... is ten times that at the surface. ...The organs collapse. The heart beats at a quarter of its normal rate, slower than... in a . Senses disappear. The brain enters a dream state.