Are you SCUBA certified? Because that's a requirement for the hotel.
In the late '90s, I tried to get SCUBA certified, and took a course. Everything went fine in the swimming pool and the shallow ocean, but once I went 30 feet down, I didn't want to continue. Something about 30 feet of water over my head couldn't allow me to relax. I think it was the realization that I couldn't just immediately surface if something went wrong. If it were only 15 feet, I could probably stay down there for a long period of time with no issue.