Some people come to the islands solely to take the plunge into the tropical Pacific and explore the underwater world. Hawaii is one of the world's top 10 dive destinations, according to Rodale's Scuba Diving Magazine. Here you can see the great variety of tropical marine life (more than 100 endemic species found nowhere else on the planet), explore sea caves, and swim with sea turtles and monk seals in clear, tropical water. If you're not certified, try to take classes before you come to Hawaii so you don't waste time learning and can dive right in.

If you dive, go early in the morning. Trade winds often rough up the seas in the afternoon, especially on Maui, so most operators schedule early-morning dives that end at noon. To organize a dive on your own, order the Dive Hawaii Guide, which describes sites on the various Hawaiian Islands, by sending $2 to UH/SGES, Attention: Dive Guide, 2525 Correa Rd., HIG 237, Honolulu, HI 96822.

Tip: It's usually worth the extra bucks to go with a good dive operator.