We walked off port and booked with Exotic Eco Adventures http://exoticecoadventures.com/ They took us to Goff's Caye, also called Gilligan's Island (because everyone wants to be stuck there!) and it was BEAUTIFUL! The snorkel guide used a metal pole to lift rocks and such and was able to find plenty of starfish, sea urchins and shrimp for us to hold. Snacks and Rum Punch were flowing for the 2 hours we had on the beach after we finished snorkeling. We were sad to go!
AWFUL! This area is PACKED with Carnival Cruise ships, everything is overpriced ($27 for SUNSCREEN!) and the beach has people PACKED in like sardines! It is LITERALLY packed towel to towel... it's gross.
We snuck away under the dock and walked around the island on the beach. We were asked twice to leave the area by a man on a jet-ski claiming it was a "private beach", but if I'm not mistaken, Carnival owns the whole Island part that the port it at, SOOO.... we stayed. We met up with some kids in their early twenties and they helped my kids find sea life like a baby lobster, a sea snail, etc... if not for them, the WHOLE day would have been awful. We got back on the boat 2.5 hours early because it was THAT bad.
We were told by friends who did a jungle excursion that it was their favorite, so DEFINITELY book SOMETHING and get the heck out of that awful port!
Lovely town, full of lovely and helpful natives. Grand Cayman is BEAUTIFUL!!! Walk around the town, walk along the beach and snorkel... you don't have to pay a lot to have a great time. Just ask some locals for advice and they will honestly and sincerely point you in the right direction without expecting anything in return.