I did a free scuba session in our hotel pool the first time I went to Hawai'i, quite a few years ago. I loved it and did the full DSD. I would have gone on and gotten certified back then if I had not gotten injured that afternoon. Years later I did another DSD and was hooked again. That's why I then got certified.
A number of years ago I was diving with an operator on a Caribbean Island, and he had an interesting tale of woe when we were driving by an abandoned hotel on the way to the dive site. The hotel had gone out of business because of some kind of shady business dealings, not for lack of occupants. He had had the concession for doing scuba demonstrations in the pool. He said MOST of the people who did those demonstrations went on to do the full DSD, and many of those went on to be certified during that week's vacation. That was pretty much his entire operation then, and he was doing very well. When the hotel went out of business, he had to change his operation completely to what it was when I used his services.
