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

[T]hese clicks are so loud you can actually feel them in your body. Your body starts heating up after a few minutes.

We know that the more you breath through your nose, the more that it's going to open... [P]eople who are habitual mouth breathers, who are also joggers... start breathing through the nose. In the beginning it's really... hard... then weeks... months go by and their noses open up... [T]he benefits... they're innumerable... not only oxygen, but it helps defend your body, humidifies... conditions air [etc.]

At sixty feet... The heart beats at half its normal rate. Blood starts rushing... toward the more critical... core. ...The senses numb, the synapses slow. The brain enters a heavily meditative state.