is not even remotely similar internally. About the only similarity would be the lungs compressing depending on the depth of the diver. And I doubt tourist snorkelers go deeper than 30ft. They mostly stay much shallower around 10ft. Also, if this was such a problem then they need to warn them to not to swim in pools. It's the same thing. I would like them in the article to explain how all the other factors impacted it and what they are. Swimming and snorkeling are basically the same. You draw your air from the surface. Just to be clear I have been PADI cert for 30+years and back then I stopped keeping my dive log when it was at over 1k of dives recorded.