Been to GC hundreds of times while working on ships. If you just go right out of the terminal area to Eden Rock dive center...like 2 minutes walking from the cruise terminal you'll be right next to some great sites. If you like caves, there are tons of them right off shore that you can do on a shore dive from their ladder. Tons of large tarpon there in the caves. If you want to swim out farther you'll hit the wall and you can descend on that. I've done many dives on that wall and seen tons of turtles, jacks, and even hammerheads. Just stay to the South of where the cruise ships are because they have damaged the reef with their anchors. If you swim straight out from Eden Rock and stay South there is no damage there. Dove many other places on the island but that is just as good as any, and you don't have to pay for a boat, and can dive at your leisure. If you want to get further away from the ship area, just walk S. along the main road a little farther and do shore dives there. With a beautiful surrounding reef, and wall about 100yds. off shore there's no need to go on a boat...honestly. You can even rent 100cu' tanks at Eden Rock...at least you used to be able to.
