Red Sand Beach, Hawaii

Red Sand Beach, Hawaii (©Monica & Michael Sweet/Getty Images)

Red Sand Beach, Maui, Hawaii
This is one of the smallest hard-to-reach beaches on our list, the most colorful, and an exotic gem even in Hawaii, which certainly has its share of rare sights where land meets sea. Red Sand Beach, which gets it name from the crumbled cinder cone from which its sand was formed, nestles in a cozy cove south of Hana Bay on the east coast of Maui. The surreally polychromatic scene: blackish red sand, sapphire sea, black lava wall blocking the breakers - with emerald-green ironwood trees all around. How does this singular strand play hard to get? The only access is by a short but narrow, steep and slippery footpath down the cinder cone. Wear your best treads.

Isaac's Bay Beach, in the Virgin Islands

Isaac's Bay Beach, in the Virgin Islands. (© John Wooldridge)

Isaac's Bay Beach,
St. Croix, U.S. Virgin Islands

"My favorite beach is Isaac's Bay Beach on the east end of St. Croix," says Wear of The Nature Conservancy. "You have to hike over rocky cliffs and down into a valley." During this moderately challenging hike, don't forget to lift your eyes and take in the stunning ocean views from the high points along the trail. "Then you get to a sandy strip of beach that's pretty much your own." There are coral reefs just beyond the surf zone with good snorkeling, though the surf is rough at times, reducing visibility and making it a challenge not to exchange injuries with the coral. Remember that the hike back to the parking lot is uphill; bring extra water.

Halape, Hawaii Volcanoes National Park, Hawaii

Keauhou Beach in Hawaii Volcanoes National Park (©NPS Photo/Jay Robinson)

Keauhou, Halape
Hawaii Volcanoes National Park, Hawaii

OK, so you think you're up for the big kahuna, our hardest-to-reach beach with some of the most gorgeous ocean waters in the world? It's Halape, in Hawaii Volcanoes National Park, 30 miles from Hilo on the island of Hawaii. In our recent conversation with a park ranger there, he ran out of fingers, then toes, naming reasons to think carefully before undertaking an outing to Halape, which requires an overnight by the beach for all but the most intrepid and well-hydrated hikers.

Here are just a few sunburned bits of what Adrian Boone had to say about this anything-but-a-walk-in-the-park: "Leaving from Chaining Craters Road, you're going to walk from an elevation of 2,600 down to sea level. You start from the middle of the 1969-1974 lava flow, walk through barren black lava, then forest, down two or three steep cliffs with loose footing, through grasslands deforested by goats and pigs. You may suck in some 'vog'--fumes from volcano smog--and encounter paper wasps and, at the campsite, cockroaches, centipedes and scorpions."

If you do make it to the water, beware of stepping on sharp reef or sea urchins; "those cuts take a long time to heal and might get infected," Boone writes. Oh, and don't forget: The hard part is the return trip, with a half-mile vertical gain back to your car. Your reward? Some serious solitude and possible sightings of ruddy turnstones, nesting hawksbill sea turtles--and those extraterrestrial blue waters.

John Rossheim is a frequent MSN contributor.