I would be really leary of some of the jet ski rentals out there. A few years back, DH & I were on a Radisson cruise and had booked an excursion that took 2 couples on a 3 hour long private snorkeling trip. We were pretty far out when we saw 2 women floating around in the middle of the ocean! We went over to see what had happened to them. Their jet ski had started throttling out of control & had dumped them into the water. They had pulled the "kill switch" but the jet ski had drifted too far away, and neither was a strong swimmer. They had been out there for over an hour at that point, too weak to wave their arms or yell. We took them back to the hotel where they had rented the darn thing, and instead of being grateful, the guys there just started yelling at the women that it must have been their fault, etc... All they could think about was how long it might have taken for these guys to notice (or care) that they were late in returning.