[Equine1952]

Submarine outside hatches use sea pressure to help hold the hatch shut. The inner pressure has to equal outside pressure to open it. In scuba diving, Inside pressure has to equal pressure on the outside so you can breathe. You take a breath at 50 feet from a dive tank and go to the surface you have to exhale all the way up slowly. I was taught to follow the small bubbles. Bolting the hatch shut even surfaced pretty much screws the riders.

[blackdog]

I remember the myth busters episode there the deep sea Diver (really a dead pig inside) had the surface air line cut to his suit. The entire pig was squeezed thru the helmet and out onto the ship deck like a tube of flesh toothpaste. Bones and all, crushed to a paste and squeezed out the air line.

Scariest thing I've ever witnessed.