I didnt read any of the other girls responses but here's mine. Stop stressing. Your guests are on vacation too let them do what they want to do on their vacay. You dont have to plan their vacay for them. Trust me they'll be fine. My guests all happened to see each other and than would meet with whomever they wanted to during the day or dinner. They also did a snorkle trip together but i didnt plan it they all did it on their own when they got there. So let your guests do what they want and you will have plenty of wedding stuff to worry about when you get there, keeping your guests occupied shouldnt be a concern. It will all be fine.