[Stodelle]

Yes, oxygen used on the surface could extend your static apnea, but underwater, it is very dangerous.

At 40 feet, under pressure, oxygen is very toxic to the human body. It causes the body to convulse, it can cause vomitting, and can cause the diver to pass out or worse.

The Navy studied this in depth during early developments of Rebreather sytems. Because the rebreather systems used oxygen with a chemical scrubber to remove CO2, it limited diving to under 40 feet. Because of their testing, and the number of injuries (of course they won't say fatalities), the Navy has set standards of diving w/in 40 feet on non-tecnical/salvage diving.

This is also why recreational scuba tanks only use an approximate 20% oxygen w/ 80% nitrogen.

All of this information, as well as the oxygen toxicity information is available in the US Navy Dive Manual.

Remember this. The tests done were performed while swimming and breathing from oxygen! No true PUBLISHED studies have been presented with holding oxygen in your lungs at ANY depth! I don't know if I'd want to truly be the guinea pig on that one!