Cave diving. I am a pretty experienced scuba diver (from living on Grand Cayman for two years), but cave diving is off the scale dangerous.

Yes, if you have excellent training and equipment you can minimize the risks, but plenty of well-trained well equipped practioners have died.

I don't know what the actual stats are, but I'll bet only sports like free diving or climbing an 8,000 meter mountain in the Himalaya's are more dangerous.

anyone have a source for statistics?