Ruth, believe me the dress code is casual, casual, casual! My hubby may take a coat, but maybe not......honestly, with the weather so tropical and the emphasis on water sports, people want to wear as little as possible! If you have pareos from earlier trips, take them - they are suitable at all times, except you may want to wear pants or a skirt at dinner. As far as must bring items, it depends on how often you will be in the water - I'm thinking of bringing reef gloves, and for sure we are bringing reef shoes. Maybe an inflatable raft for the lagoons? I'm sure others will have some ideas..