Guys, the best purchase I made before the trip was a "real" underwater camera. Got it at Target for $14.99 which included the batteries and a roll of Kodak 400 film. I wished I had bought 2 as DH and DD squabbled over it all the time when they were snorkeling.
Used it again the other day at Typhoon Lagoon. For the price, IMHO, it's well worth it compared to the disposables, and more environmentally friendly, too.