If you snorkel or scuba dive, the coral reef is excellent. On my scuba trips with Southpoint divers (where I got certified) I saw nursary shark, another type of shark, moon jellies, baraccuda and a lot of other fish and corals. Althought from what I heard, Ike did a bit of damage to the reefs.
Alonzos is great for happy hour 4-6:30pm where you get half price drinks and half price appetizers.
Damn Good Food take out opposite Galleon and around the corner from Alonzos is great for sandwiches, etc. and I had an excellent blackened grouper sandwich with fries.
Half Price Raw Bar at the historical seaport has happy hour with 50cent oysters and on Wed 6-9, all you can eat crab legs.
Sloppy Joes is good for drinks and have live music on the weekends. So does Green Parrot.
I liked a local spot Hogfish Grill on Stock Island but it can be easy to get lost without a GPS.