If you like big, wide, empty, gold-sand beaches and crystal-clear, cobalt-blue water full of bright tropical fish -- and who doesn't? -- go to Lanai. With 18 miles of sandy shoreline, Lanai has some of Hawaii's least crowded and most interesting beaches.

Hulopoe Beach

In 1997 Dr. Stephen Leatherman of the University of Maryland (a professional beach surveyor who's also known as "Dr. Beach") ranked Hulopoe as the best beach in the United States. It's easy to see why. This palm-fringed, gold-sand beach is bordered by black-lava fingers, protecting swimmers from ocean currents. In summer Hulopoe is perfect for swimming, snorkeling, or just lolling about; the water temperature is usually in the mid-70s (mid-20s Celsius). Swimming is usually safe, except when swells kick up in winter. The bay at the foot of the Four Seasons Resort Lana'i at Manele Bay is a protected marine preserve, with schools of colorful fish and spinner dolphins. Humpback whales cruise by here in winter. Hulopoe is also Lanai's premier beach park, with a grassy lawn, picnic tables, barbecue grills, restrooms, showers, and ample parking. You can camp here, too.

Hulopoe's Tide Pools -- Some of the best lava-rock tide pools in Hawaii are found along the south shore of Hulopoe Bay. These miniature SeaWorlds are full of strange creatures: asteroids (sea stars) and holothurians (sea cucumbers), not to mention spaghetti worms, Barber Pole shrimp, and Hawaii's favorite local delicacy, the opihi, a tasty morsel also known as the limpet. Youngsters enjoy swimming in the enlarged tide pool at the eastern edge of the bay. When you explore tide pools, do so at low tide. Never turn your back on the waves. Wear tennis shoes or reef walkers, as wet rocks are slippery. Collecting specimens in this marine preserve is forbidden.

Polihua Beach

So many sea turtles once hauled themselves out of the water to lay their eggs in the sunbaked sand on Lanai's northwestern shore that Hawaiians named this beach Polihua, or "egg nest." Although the endangered green sea turtles are making a comeback, they're seldom seen here now. You're more likely to spot an offshore whale (in season) or the perennial litter that washes up onto this deserted beach at the end of Polihua Road, a 4-mile jeep trail. There are no facilities except fishermen's huts and driftwood shelters. Bring water and sunscreen. Beware of the strong currents, which make the water unsafe for swimming. This strand is ideal for beachcombing (those little green-glass Japanese fishing-net floats often show up here) and fishing.

Shipwreck Beach

This 8-mile-long wind-swept strand on Lanai's northeastern shore -- named for the rusty ship Liberty stuck on the coral reef -- is a sailor's nightmare and a beachcomber's dream. The strong currents yield all sorts of flotsam, from Japanese handblown-glass fish floats and rare pelagic paper nautilus shells to lots of junk. This is also a great place to spot whales from December to April, when the Pacific humpbacks cruise in from Alaska. The road to the beach is paved most of the way, but you really need four-wheel-drive to get down here.