The catamaran excursion was great as far as the entertainment and friendliness go. You are handed a drink the moment you step onto the boat, and laugh the entire time you're on the catamran. Opt to take the island drop-off instead of snorkeling. Snorkeling near the underwater statue was very hazy, and we actually swam in garbage (cups, cans, plastic silverware, etc.), and the fish were really not plentiful.
We had a great time on the catamaran cruise, for we met a great deal of people from around the country. If you want to take a snorkeling trip, take advantage of another Carribean detination with clear snorkeling advertures. We still feel though, that Acupulco Bay is very pretty and is separated by the old and new section. The old section of the bay is not allowed to build up skycrapers and such--they are to keep it looking old.