Ross and the list,
Kobie pretty well spelled it out about narcosis and the bends. Narcosis
starts about 80 feet (25 or so meters) and gets worse with depth. It is like
being drunk and moving in slow motion. It's only happened to me once at 130
feet. The bends can happen at any depth if you ascend too fast.
Divers Alert Network (DAN) does comprehensive research into diving accidents.
They are located in Durham, NC. They have a web site but I don't have the
address with me. They should be able to provide you with statistics about
diving.
Howard
Naples, Fl.