Yeah I went scuba diving last year, it was really good! Just walk down the waterfront towards Eden and Es Paradis (coming from the Westend) and there will be a sign somewhere. Speak to the guy there and arrange a time when you want to go diving. You usually have to book it a day in advance. It is pretty cool, but I wasn't in the best of health when I was doing it. I had been clubing at Cream all night, then got back to my apartment to change into some other clothes, then set off to go scuba diving!