[A] few years ago a French researcher and a Belgian freediver... thought "What if we try freediving with whales? Maybe we could get close enough... a… - James Nestor

"There are as many ways to breath as there are foods to eat," said one... instructor... Another diver told me that some methods of breathing will nourish our brains... others hasten our death.

[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.

[B]est of all, divers will tell you, "It's open to everyone."