Glad you enjoyed the pictures! Most of the posted shots were taken with a Canon D10 or an Olympus TG820. A few of the earlier ones with a Pentax W80.
I would recommend you spend a few more dollars and consider a Canon D20 or something from the Olympus TG800 series. The underwater and above water image quality will be noticeably better than the two you are considering.
I know there have been some highly rated Panasonic and Sony cameras over the last few years, but most ratings/reviews of point and shoot UW cameras never actually test real world performance when snorkeling, but rather use laboratory environments. Canon and Olympus products seem to consistently provide the best snorkeling results.
On Grand Cayman you can rent UW cameras from Cathy Church (no need for the housing when snorkeling). I think you can look on-line for other by mail underwater camera rentals options. Not sure if it is really cost effective, but if it is you can at least test a model before buying.