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 Oahu Snorkelers and Shore Divers Guide, by Francisco B. de Carvalho, from University of Hawaii Press.
Tip: It's usually worth the extra bucks to go with a good dive operator.
Snorkeling is one of Hawaii's main attractions, and almost anyone can do it. All you need is a mask, a snorkel, fins, and some basic swimming skills. In many places, all you have to do is wade into the water and look down at the magical underwater world.
If you've never snorkeled before, most resorts and excursion boats offer snorkeling equipment and lessons. You don't really need lessons, however; it's plenty easy to figure out for yourself, especially once you're at the beach, where everybody around you will be doing it.
While everyone heads for Oahu's Hanauma Bay -- the perfect spot for first-timers -- other favorite snorkel spots include Kee Beach on Kauai, Kahaluu Beach on the Big Island, Hulopoe Bay on Lanai, and Kapalua Bay on Maui. Although snorkeling is excellent on all the islands, the Big Island, with its recent lava formations and abrupt drop-offs, offers some particularly spectacular opportunities. Some of the best snorkel spots in the islands -- notably, the Big Island's Kealakekua Bay and Molokini Crater just off Maui -- are accessible only by boat.
Some snorkeling tips: Always snorkel with a buddy. Look up every once in a while to see where you are and see if there's any boat traffic. Don't touch anything; not only can you damage coral, but camouflaged fish and shells with poisonous spines may also surprise you. Always check with a dive shop, lifeguards, or others on the beach about the area in which you plan to snorkel and ask if there are any dangerous conditions you should know about.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.