Magician David Blaine just spent a week in a goldfish bowl. Why do people do this? And 7 minutes holding your breath? The longest I went once was about a minute and a half. They say that skydivers don't need to hold breath at all during freefall. Apparently when your careening towards the ground at 120 mph, the air goes right through your skin into your bloodstream.
I'm thinking if Mr. Blaine were to do this stunt over again he could mount sensors on his body that blow pure oxygen into his body, as in freefall.