[Jon]

I have read about people breathing 02 on the surface and doing really long statics in the pool- I thought that Umberto did 19 minutes this way once.
Of course 02 is toxic below 20' and its dangerous side effects can be intensified by cold and medication. This would not be a good idea to try. It is more of a "controlled experiment" that some people have subjected themselves to.
I do remember Eric Fattah talking about the possibilities of a 20 minute reef dive in 15' feet of water on one breath of 02. I just don't know of anyone who would want to take the risk of a black out or a seizure.

Jon