Any SCUBA divers here?

[justinl]

yeah just swim a few laps in a 25m long swimming pool. you can go as fast or slow as you want and the instructor will let you know when to stop.

one thing to think about is the fact that when you look up you won't see anything. One friend of mine (we did the padi open cert together) was a little nervous during her first dive when she looked up and couldn't see the surface. She quickly got over it though by being thoroughly distracted by various things on the sea floor.