We'll be on the 12/15 Enchantment of the Seas, and making a stop here as well. We are looking at possibly going scuba diving here, although I've heard mixed reviews about diving here in December. We've been to Keys in December, and have always had great weather, but rough seas.
Walking around town is a lot of fun...it's a good place to rent bikes or go shopping. There are kiosks near the ship, as you exit, that offer parasailing and jet skis.