Six islands in an open ocean make for endless choices, but relax. Michele Kayal did the work—selecting the best, no matter what your passion

"Slow down! This ain't the Mainland," reads a popular Hawaii bumper sticker, but beware the catch: Go too slow and you'll miss all there is to do. Forget about the recreational Rambos after the extreme scene—parasailing, hang gliding, and skydiving. Even the mildest "today we snorkel, tomorrow we sail" vacationers will find so many ways to have fun that they might just save that dime-store paperback for the flight home.

The area code for Hawaii is 808. Prices quoted are for the current month, and activity costs are per person per day, unless noted otherwise.

Biking
On a mountain bike, you can zip down Lanai's brick-red plantation roads or over Molokai's miles of tricky trails. But adrenaline junkies have the widest choice on Oahu, where dirt tracks cut between thousand-foot cliffs and through rain forests that fringe the sea. Bike Hawaii hits the highlights (877-682-7433; www.bikehawaii.com; tours, $75–$95).

Big Island bikers can pump their way up the Pacific's tallest peak one day (take snow gear!) and across a coastal lava plain the next. Mount up at Mauna Kea Mountain Bikes and head for the rolling pastures or the rocky, pig-inhabited terrain of Mud Lane (888-682-8687; www.bikehawaii.com/maunakea; rentals, $30).

Hard-core bikers can grab a cycle and cut across Kauai on the Powerline Trail with wheels from Outfitters Kauai (888-742-9887; www.outfitterskauai.com; rentals, $30–$45). Aloha Kauai Tours treks through an old sugar plantation (800-452-1113; www.alohakauaitours.com; treks, $100).

Diving and Snorkeling
Staying on top of the ocean is like standing outside the circus tent, Dave Barry once quipped. Snorkel or dive in the Big Island big top called Kealakekua Bay with Fair Wind Cruises (800-677-9461; www.fair-wind.com; snorkel tours, $93; dives, $132–$171). Hover below giant, gliding manta rays with Jack's Diving Locker (800-345-4807; www.jacksdivinglocker.com; snorkel tours, $50–$70; dives, $95–$185).

Snorkel among swarming parrot fish and yellow tangs at Molokini with Kai Kanani (879-7218; www.kaikanani.com; snorkel tours, $39–$89). Dive there—or at Lanai's exalted Cathedrals, where the sunshine streams through lava tubes like light through stained glass—with Trilogy (888-628-4800; www.sailtrilogy.com; snorkel tours, $95–$169; dives, $144–$228).

Or grab your own mask and fins at Snorkel Bob's and explore the state's marine preserves. Mile-wide Kealakekua Bay hosts legions of octopuses and butterfly fish. Green sea turtles haunt the underwater canyons of Maui's Honolua Bay (800-262-7725; www.snorkelbob.com; rentals, $3–$8). Oahu's Hanauma Bay Nature Preserve is crowded for a reason: great snorkeling and a new $13 million education center (395-2211; www.hanaumabayhawaii.org; entry fee, $5; rentals, $6).

Fishing
On the Kona Coast, big-game fish and big-money tournaments lure sportsmen and millionaires hoping to land a "grander," one of those thousand-pound marlins you thought Hemingway just dreamed up.

Kona has the largest fishing fleet in the state, and the Charter Desk will match your skills to one of 50-plus boats. Be ready to hook anything from an eight-pound skipjack to a half-ton billfish, which could get you strapped into a fighting chair (888-566-2487; www.thecharterdesk.com; half-day, $115; full day, $170). Quint wannabes can go shark hunting through Sportfish Hawaii. The agency also books regular charters on four islands (877-388-1376; www.sportfishhawaii.com; half-day, $119–$140; full day, $150–$249), as well as freshwater angling for famous fighting peacock bass on Oahu and Kauai (half-day, $265–$325; full day, $375–$425). Note: Local etiquette lets the captain keep your fish. If you want to mount your catch or take home fillets, say so when booking.

Hiking
Yeah, yeah, sun and sand—we know, we know. But some of Hawaii's greatest charms lie just a short hike from your beach towel. The Department of Land and Natural Resources has information on guides and hiking throughout the state (www.hawaiitrails.org), but here is a selection of the best:

On the Big Island, the Hawaii Volcanoes National Park visitors center provides maps and advice (985-6000; www.nps.gov/havo/home.htm), but Hawaii Forest & Trail has naturalist-guided treks to lava tubes, steam vents, and of course the red stuff (331-8505; www.hawaii-forest.com; treks, $95–$155).

Waimea Canyon—"the Grand Canyon of the Pacific"—plunges 3,400 feet through Kauai's Kokee State Park, begging hikers to sample its blue-and-red oxide hues. Get a $5 map from the Kokee Natural History Museum (335-9975; www.aloha.net/~kokee).

Trails to burnt-red cinder cones coil the 10,023-foot summit of Maui's Haleakala National Park (572-4400; www.nps.gov/hale), and you can tramp around with the experts from Hike Maui (879-5270; www.hikemaui.com; guided hikes, $60–$140).

The folks at Molokai Outdoor Activities will take you from 3,000-foot sea cliffs to secluded sandy beaches (877-553-4477; www.molokai-outdoors.com; guided hikes, $35–$150).

And here's a revelation: Some of Hawaii's very best hikes are on Oahu. Scoot to the tide pools below Makapu‘u Point or trek across the windward ridges. Hit the trails solo or with the Hawaiian Trail and Mountain Club (674-1459; www.geocities.com/htmclub; donation for nonmembers, $2).

Horseback Riding
The Big Island claims to have had organized ranches—and therefore cowboys, called paniolos here—before Texas had them. At Paniolo Adventures, a canter through Hawaii's big-sky country makes people wish they'd figured out their camera's panorama function (889-5354; www.panioloadventures.com; riding tours, $73–$124).

Peter Baldwin is a fifth-generation Maui man whose family is the stuff of local legend: They once owned Haleakala crater. At Piiholo Ranch, he calls his cattle like lap dogs and spins tales from diaries left by missionaries, politicians, and ranchers (866-572-5544; www.piiholo.com; riding tours, $120–$190). Pony Express Tours offers daily guided rides into the crater (667-2200; www.ponyexpresstours.com; riding tours, $55–$190).

For more than just a ride, help round up the herd at Kauai's Princeville Ranch Stables (826-6777; www.princevilleranch.com; roundup, $120; riding tours, $65-$170). And what better party trick than making cattle run an obstacle course? Learn how at Molokai Ranch (866-269-3900; www.molokaifishanddive.com; riding tours, $80).

Kayaking
Kelii's Kayak Tours will get you to Maui's gorgeous turtles (888-874-7652; www.keliiskayak.com; from $49 for two hours). But if you want bragging rights, conquer Kauai's Na Pali Coast. The malevolent 17-mile paddle promises seasickness and six-foot swells, but Kayak Kauai also delivers sea caves, waterfalls, and expensive dolphin escorts (800-437-3507; www.kayakkauai.com; tours, $60–$175). Kauai's half-dozen rivers offer more-pacific journeys to bird preserves and swimming holes. With Outfitters Kauai, you can punctuate paddling with a zip line that whizzes you across rivers and waterfalls (888-742-9887; www.outfitterskauai.com; kayak tours, $80–$94; zip line tour, $90).

Museums
At the Maui Ocean Center, divers—presumably those addled by too many air bubbles—are invited to jump into the main exhibit to meet the resident tiger shark (270-7000; www.mauioceancenter.com; admission, $20; shark dive, $190).

The Honolulu Academy of Arts has a well-respected Asian collection (532-8700; www.honoluluacademy.org), and the Hawaii State Art Museum showcases nearly 300 acclaimed Hawaii artists—such as Jean Charlot, Herb Kane, and Pegge Hopper—that you probably won't see elsewhere (586-0900; www.hawaii.gov/sfca).

Diamond Head meets Damascus at Shangri La, the five-acre Islamic fantasy built in 1937 by tobacco heiress Doris Duke. Who knew you could find glittering Ottoman ceramics and painted Moroccan ceilings so close to Waikiki? (866-385-3849; www.shangrilahawaii.org; admission, $25.)

Forget The Poseidon Adventure (if you haven't already): Stop at the Big Island's Pacific Tsunami Museum for footage and stories from people who survived the real thing (935-0926; www.tsunami.org).

Sailing
Catamarans and cocktail cruises clutter Hawaii's harbors, but there's only one way to feel like Gatsby: Get your own boat. Charter one of the Honolulu Sailing Co.'s dozen vessels for three hours or three weeks (they teach sailing too). Shoot the Kaiwi Channel on a 50-foot sloop, anchor off the forbidden isle of Niihau in a 120-foot floating mansion, or ask for the sister ship to one owned by President Kennedy (239-3900; www.honsail.com; from $60 for three hours to $10,000 per day).

If it's salt spray you're after—on your face and in your drink—take a sailor's sail aboard the America II. The 1987 America's Cup contender searches for fast winds off Maui daily (888-667-2133; www.galaxymall.com/stores/americaii; sails, $37 for two hours).

Surfing, Etc.
Mark Twain declared "none but the natives" could master surfing, and here's your chance to prove him wrong. Waikiki's sandy bottom and gentle waves make it an ideal place to attempt the ancient sport of "wave sliding." Snag a beachboy from one of the oceanside concessions and take a lesson (from $35 for one hour), or let the Hans Hedemann Surf School teach you the breaks. Hedemann has personally tended the Blue Crush dreams of Adam Sandler and Cameron Diaz (great surfer, he says), and he caters to mere mortals at six Oahu locations, including the legendary North Shore (924-7778; www.hhsurf.com; lessons, from $50 for one hour). But don't head to the North Shore on your own: Fast-moving tubular breaks like Pipeline and 30-foot waves make this an experts-only place in winter.

On Maui, big-surf fanatics get themselves towed into Jaws, where the waves are taller than buildings. If you just want to try the small stuff, John Browne and His Maui Beach Boys guarantee you'll make it in upright, or you get to go again (283-7114; mauibeachboys@aol.com; lessons, from $49 for two hours). But Maui's real obsession is windsurfing. They come from around the world to converge on Ho‘okipa Beach. Hawaiian Island Surf and Sport caters to experts with its enormous fleet of equipment and to beginners with lessons in everything from windsurfing to kiteboarding—think hang gliding with regular touchdowns on the water (800-231-6958; www.hawaiianisland.com; windsurfing, two-and-a-half-hour lesson, $79).

Swimming
Each year, the scientist they call Dr. Beach picks the best stretch of sand in America (how do you get this job?), and Hawaii has grabbed the No. 1 slot eight times in the last decade. So it's hard to go wrong.

Two miles of tawny sand cover Oahu's Kailua Beach, where nearby pyramid-shaped islands urge you to hop in a kayak. Thirty-foot waves pound Waimea Bay Beach in winter; in summer, nothing but dolphins break the blue-green glass.

Maui didn't put one of its top resorts at Ka‘anapali Beach for nothing, but many locals prefer Kahekili Beach, where angelfish swarm the reef.

Hapuna Beach draws Big Islanders who crave waves, and giant manta rays commune with evening swimmers at nearby Kaunaoa Beach.

Your lounge chair shares a habitat with the endangered monk seal on Kauai's Poipu Beach; learn about the species at www.kauaimonkseal.com.

Touring
Chomp a piece of sugarcane, the crop that shaped Hawaiian history, on Kauai's Gay & Robinson Field & Factory Tour, which explores one of the state's two remaining sugar plantations (335-2824; www.gandrtours-kauai.com; $30).

Book with Molokai Mule Ride to descend the 26 switchbacks to the windswept sadness of Kalaupapa National Historical Park, the peninsula to which generations of Hansen's disease patients—lepers—were once exiled, and where a few dozen still live (567-6802; www.nps.gov/kala; 800-567-7550; www.muleride.com; $150).

Cultural curiosity meets caffeine addiction at the Big Island's Kona Coffee Living History Farm, where kimonos in the closet and beans in the field capture the life of one Japanese family that—along with Portuguese, Filipino, Hawaiian, and other laborers—helped create one of Hawaii's most famous crops (323-2006; www.konahistorical.org; tours, $15).

Whale Watching
Humpbacks run so thick in Maui's winter waters you could practically walk across them, so any boat will stumble on a few. But the Pacific Whale Foundation's fleet of eco-conscious luxury catamarans include science-educated naturalists as guides, and profits go to conservation efforts (800-942-5311; www.pacificwhale.org; whale watches, $20).

Whales are to kayaks as Hummers are to Matchbox cars, but the experts at South Pacific Kayaks & Outfitters say coming eye-to-eye with a humpback and feeling whale song set your hull aquiver like a tuning fork are worth the palpitations (800-776-2326; www.southpacifickayaks.com; whale watches, $59).

And here's the big secret: Hawaii has whales year-round. Captain Dan McSweeney's Whale Watch visits the Big Island's plentiful migrant humpbacks, and once they're gone he shows off resident species like 60-ton sperm whales (Moby Dick was one of these) and melon-headed whales that sometimes travel in pods of a thousand or more (888-942-5376; www.ilovewhales.com; whale watches, $60).

Reading
Off the Beaten Path's quirky general guide to the islands has notes on less-visited sights (Globe Pequot Press, $15). But dozens of single-subject guides target the islands' best places for surfing, camping, fishing, golf, and even flying. Audrey Sutherland's Paddling Hawaii details kayaking routes and gives tips on catching your own dinner (www.uhpress.hawaii.edu; $18). The Surfer's Guide to Hawaii, by Greg Ambrose, covers superior breaks and wave etiquette (Bess Press, $12). Richard McMahon's Scenic Driving Hawaii lays out 18 tours on six islands (Falcon, $15), while Waikiki: Nine Walks Through Time, by Veneeta Acson, leads the peripatetic visitor through history (www.islandheritage.com; $14). Stuart Ball's Hikers Guide to the Hawaiian Islands is a backpacker's staple (University of Hawaii Press, $20).