[B]reathing research has been taking place... in the muddy digs of ancient burial sites... dental offices, and... mental hospitals. - 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.

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.

25-50% of the population... breath through their mouth. ...[This causes] neurological problems... respiratory problems... snoring, , even s [etc.]