Hotel?? If you are the flexible type you dont need reservations.. However. If its your first time I would make arrangements for at least a couple of days.. Walk around ,Hang out and decide where you want to stay.. As far as Diving dont bother there are so many operators, they go every day , just pick an operation you like, make arrangements the afternoon before and go...Most will pick you up at your Hotel dock if you are not staying within walking distance..