Your chance to swim with the dolphins. Its amazing. Before you are allowed to swim with them, you must take an introductory course that allows you to touch them and even put your hand in their mouth if you want to ! Then you are qualified to snorkel with them. New rules as of January 2004 are that you must wear a life jacket but that doesn't diminish the experience. These are wonderful animals that you can touch and swim with. Everyone should do this!
When in Palau, definately check out the rock islands. You can see them while out diving, kayaking or flying over them. Whatever you do, see them. Sams tours has dive boats and rents kayaks and Belau air lets you fly over them. This view is taken from the hamlet of Koror called Meyuns.