I agree with Rob, get there early and just RELAX and enjoy the day. There are not a massive choice of things to do, but the ray lagoon and coral reef are attractions that change each time you go through.
Oh I REALLY enjoyed a frosted Pina Colada slushy at the end of the day while watching the trainers getting some play time in with the dolphins, everyone seemed to be having a great deal of fun and it was a great finish to the day.