1. Mammoth Cave National Park, Kentucky: Find Your Way in the Dark
Slither through a nasty crawlway called No Name Pass, one of the highlights of Mammoth's Wild Cave Tour, and you just might be in the quietest place on Earth. For about one body length, the passage clamps down so tightly you have to turn your boots sideways to worm through, and all sound is absorbed by the limestone walls: You can scarcely hear the thump of your heart. And if you switch off your flashlight, you'll be in darkness so complete it'll make a coffin seem bright and noisy.
Vitals: For info on the park's Wild Cave Tours ($46), visit www.nps.gov/maca.
2. Kenai Fjords National Park, Alaska: Return to the Ice Age
Call it a staircase to the Ice Age. At the apex of the switchbacking, four-mile (4.6-kilometer), 4,000-foot (1,219-meter) grunt up the Harding Icefield Trail, you reach a desolate landscape of snow and ice, unbroken but for a few craggy peaks—a place that fits the image of the North Pole better than the Pole itself. Suddenly, getting your butt kicked for several hours feels justified. Plan on fog, rain, wind, sweat (pack dry clothes for the return), and company—black bears diffidently grazing and mountain goats taunting your approach.
Vitals: For hiking info, visit www.nps.gov/kefj.
3. Great Sand Dunes National Park and Preserve, Colorado: Ride Wild Dunes
Huck, shred, freeride, or just glide down sand slopes 750 feet (228 meters) above the San Luis Valley floor at Great Sand Dunes. Besides being an improbable fluke of geology—a sand sea at the base of Colorado's Sangre de Cristo Mountains—the park is the place in the States to sandboard. To do it right, bring an old beater snowboard (the bindings will get trashed) and plan on a tough, five-mile (8-kilometer) hike to Star Dune, the tallest in the park. At least you won't have to pay for a lift ticket.
Vitals: For park maps and info, visit www.nps.gov/grsa.
4. Biscayne National Park, Florida: Get a Grouper to Smile
Biscayne's 173,000 acres (70,010 hectares) are 95 percent underwater—the largest marine park in North America—and sit at the north end of the world's third largest coral reef system. Surprisingly, that portion of reef, just 25 miles (40 kilometers) from Miami, is healthier and less visited than those farther south in the Keys. The park's sole concessionaire, Biscayne National Underwater Park, runs only two two-tank dives a week. Divers can see more than 200 species of kaleidoscopic fish—amazingly curious since they're so seldom approached—flitting about in water that appears to have been bottled by Tanqueray. On the weekly deepwater dive to The Wall, there's a strong chance of seeing big pelagics such as nurse sharks, southern stingrays, and goliath groupers.
Vitals: Biscayne National Underwater Park offers dives only on weekends ($64; www.nps.gov/bisc).
5. Acadia National Park, Maine: Hike with Your Hands
You'll never feel more quadrupedal than on an ascent of the Precipice Trail in Acadia National Park. The vertiginous route scales a steep, thousand-foot (305-meter) granitic dome in one and a half miles. "Persons have fallen and died on this mountainside," reads the jolly sign that welcomes you to the trail. No worries: The only skills you'll need are some boulder-hopping at the beginning and judicious grabbing of iron rungs and rings to summit. The payoff is a view of the east side of Mount Desert Island—all ponds, meadows, mountains, and offshore islets.
Vitals: If peregrine falcons are nesting on the mountain in early summer, the trail will be closed. But rangers will set up a spotting scope so you can see the raptors in action. For updates on closures, visit www.nps.gov/acad.
PLUS: The Top Five
The Thrill Factor
Five unexpected itineraries that scream action
Trips Through the Ages
Five classic adventures that will never go out of style
Five off-the-charts escapes that reach deep into the wild
Moments to Live For
Five of life's most essential experiences, done perfectly in the parks
Pick up the June/July 2006 issue for 50 top adventures in the national parks; how to move to Montana; the best ten-day Brazil vacation; 11 instant weekend escapes; and new watches, cameras, and sunglasses for summer.
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