simonov wrote: I was NAUI certified about 20 years ago, but soon gave up SCUBA because I became concerned there were simply too many ways to die, especially if it wasn't something you were going to do with great regularity (like at least once a month or so). But I got the impression my instructor was different from most of them. At every point of our instruction, he emphasized the likelihood (indeed, the certainty) that our gear would fail, and drilled us on procedures to use in the event of gear failure. Later my dive buddy and I got into the habit of practicing ESAs during every dive (only partly because they are kind of cool). I gather most certification classes take precisely the opposite approach, that they emphasize an extreme reliance on well-functioning equipment to make the students confident in the water as quickly as possible. There, again, is your problem, and the essential difference between diving and mountaineering.
I got my certification (PADI) also about 20 years, but have taken advanced courses (NAUI) over the years. The instructors I had clearly imparted dangers faced even with short (i.e., 60 ft. or less), recreational dives: decompression sickness, embolisms, busted eardrums, etc. The parallels with mountaineering are interesting. I think like mountaineering, equipment malfunction is not in the forefront of risks (unless you misuse the equipment of course).
Changing environmental conditions, not paying attention to your tables/computer, not being able to control a needed safety stop, are more common risks I think. And if you beach dive, you need extra skills (surf entry and exit for one) not needed with open water diving off boats. SCUBA even has the bouldering equivalent of technical rock climbing in free diving with weight belt.
Also like mountaineering, shit happens despite our best efforts. I was bent slightly once (didn't need the chamber though) and busted my eardrums once. And like climbing and mountaineering, learning SCUBA rescue skills sure makes you feel a lot more confident. Getting a scuba rescue certification was by far the best scuba course I ever took. So if you get back to it, take a rescue course (I did hate the underwater swim requirement though b/c it took me two tries to pass it).