Most resorts spray for mossies regularly so they're not as big an issue as you'd expect. I'm normally breakfast, dinner and tea for the wee winged b**tards but managed to get through my entire honeymoon bite-free (well, almost) :o) - if you do decide to do one of those little 'excursions' to a remote island, however, you'll be wanting a mumu, a yashmak and some wellies. Oh, and welding mitts. King and Queen for a day my arse.
Sharks can be a problem if you're of a nervous disposition. And coral. Oh, and hermit crabs can give you a nasty nip.