Worst dive...well, so many good ones, even if scary or whatever. Former pro diver with Cousteau and we did some crazy stuff. I guess my worst dive was more recent. I had been overnight in an underwater habitat. I knew my tank was full upon entry and I'd definitely turned it off. So I stupidly did not check the air the next morning before a dive. We left the habitat, my buddy rounded the corner and was out of sight, I was hung up on an anchor line (my tank valve got snagged)...I had no air and was alone. Relatively shallow at just about 35' but almost bought the farm. Managed to stay calm, unhook myself and surfaced safely. Rather scary, so that was my worst.