> Please remain within your training limits as at least 2 OW divers have died there within the past 2 years.
One interesting (to me) example was a few years ago, witnessed a snorkeler taking a breath from an air pocket in the 17 FFW East tunnel. My buddy tactfully advised her that it wasn’t a good idea. She said it was OK, she knew to exhale on the way up.
Well, that means she understood Boyle’s Law, but probably didn’t understand the chemistry involved in mixing CO2 and limestone, or the physiology of the elevated levels of CO2. Guess one out of three ain’t bad.