These were recovered still full after 40 years on the bottom. That is a SP Pilot.This reminds me of something sort of fun. I once retrieved a friend's lost inflation bottle after it had been in the water for about a year. The diaphragm was distended from the first stage by maybe an inch. It was intact and the (pressurized, of course) stage and tank were dry inside. We were amazed it hadn't blown out or leaked!