Shorts,Sunscreen,insect repelllant with deet,MONEY,bathing suits,flip flops,tennis shoes if going boating or water socks. If you snorkle you may want your own mask & fins but they can be rented also,MONEY,a sense of adventure and sense of humor & at last more MONEY. Do you have any idea of the types of activities you want to participate in if any? The parasailing is great so bring a one time use camera to take pictures with, that way if you drop it no big loss oh yes and MONEY. Actually you can spend alot or not alot depending on how heavy you drink and how many places you want to go. The side trips are nice but I really enjoy staying on the island especially if you are there for a short time say 5 to 10 days.