Jared Ogden, Professional Climber

The Karakoram mountains of Pakistan are home to K2, the world's second highest peak at 28,251 feet. For Ogden, a world-traveling expedition climber, the range's skyscraping granite spires, including the Great Trango Tower and Shipton Spire, make the Karakoram an archetypal and incomparable place. "I've never seen such beautiful mountain architecture as in this range," he said. The Karakoram is one of the highest mountain ranges in the world, too, with dozens of peaks stretching above 20,000 feet in elevation.

Vince Anderson, Professional Climbing Guide

Straddling the Alaska/Yukon border, the St. Elias Range features snowy and socked-in mountains stretching nearly 20,000 feet into the sky. For Anderson, the range exemplifies all things wild, rugged, remote and vast. "It is a true mountain wilderness with huge glaciers, high peaks, big relief and much wildlife," he said. Being close to the ocean, the range offers some of the biggest vertical relief on the planet. For example: Mount Saint Elias, at 18,008 feet, is just ten miles from the icy waters of a sea-level fjord.

Abby Watkins, Professional Climbing Guide

Older and more remote than the Rockies, though much less known, the Selkirk Mountains of British Colombia extend north from Idaho far into the wilds of Canada. Deep forests, abrupt mountain faces and glaciers are part of the allure. Watkins loves the range's alpine climbing and backcountry powder skiing. "The glaciers are big, the rock is good quality and the skiing in winter is unbeatable," she said.

Will Gadd, Professional Climber/Paraglider/Writer/Producer

Gadd has traveled to most of the major mountain ranges in the world. But the Canadian Rockies, especially the Canmore-Mt. Robson corridor, is his favorite alpine destination. Rock and ice climbing, as well as high alpine mountaineering, are part of the appeal. "These mountains are truly wild," he said. Gadd noted that it's possible to hike hundreds of miles in this range without ever crossing a road. He said picking a top route in the Canadian Rockies would be like "choosing a favorite dish from an unimaginably large buffet."

Vera Schulte-Pelkum, Climber/Geophysicist

As a working geophysicist and a climber, Schulte-Pelkum said she has developed a personal relationship with the Colorado Front Range of the Rocky Mountains. This line of mountains, extending south from the Wyoming border into Colorado, features several summits above 14,000 feet. The steep terrain provides alpine, rock and ice climbing--as well as skiing--nearly year-round, according to Schulte-Pelkum. She also has a soft spot in her heart for the range's geologic past: "The high peaks are flanked by the remnants of an older mountain range that was lifted up in a collision with the supercontinent Gondwana and then completely eroded away before the dinosaurs showed up on the scene."

Ed Viesturs, Professional Climber

Seattle-area resident and renowned professional climber Ed Viesturs has summitted the 14,410-foot Mount Rainier 198 times. "It offers so much variety and gives you a taste of the Himalayas, especially in winter," he said. Viesturs trained for years on the mountain's flanks, guiding groups on moderate routes and pushing limits on extreme and exposed ridgelines. Though Rainier often steals attention, Viesturs said the Cascades are full of hidden gems, including Mount Adams, Mount St. Helens and the sharp granite spike of Mt. Stuart. "No other range in the lower 48 has this variety."

Alaska Range

Jack Tackle, Professional Climbing Guide

This 400-mile-long mountain range in south-central Alaska is a mountaineering paradise, with extraordinarily remote routes that are as technical and challenging as anything on the planet. The range's most well-known peak is the 20,320-foot Mount McKinley. Tackle first visited the Alaska Range in 1979; he's since returned dozens of times for 11 significant first ascents. "The Alaskan Range can be Himalayan in scale," he said. "Plus, there is the benefit of having almost 24 hours of daylight in the summer months for continuous push ascents."

Kevin Thaw, Professional Climber/Writer/Speaker

The mountains of Argentine Patagonia--specifically the spires of the Fitzroy/Cerro Torre massif--are archetypal granite peaks that cut a sharp silhouette on the South American sky. Jaw-dropping heights, including vertical faces that fall away for almost a mile straight down, make this area a climbing mecca. For Thaw, who has climbed in Patagonia almost every year since 1998, the 10,280-foot Cerro Torre exemplifies the region's absurd alpine allure. "Dr Seuss might conjure a caricature that looked all too similar to this peak," he said.

If you like smoking mountains, Stromboli is the place to go. The best known of several active volcanic islands located north of Sicily, this conical vision rising straight out of the sea is as unpredictable as the weather. In order to trek through this unique landscape, you must join a guided tour, most of which head off on the strenuous three-hour climb in the late afternoon. Once near the summit, you enjoy a Mediterranean sunset and return as darkness falls. In the heat of the summer, however, some tours also go up at night and come down in the early morning. The cost can be as low as $16.

For more information: Wiki Travel

With 300,000 people crowding Japan's Mt. Fuji during its relatively short summer climbing season, this adventure is as much of a social affair as it is a communion with nature. In fact, mountaineer Greg Slayden says that Fuji, a volcanic slag heap, is far more beautiful when you regard it from afar than when you're standing on it. Most hikers head part of the way up on day one and sleep for several hours in one of many huts (reservations required) before setting out in the middle of the night hoping to see a legendary red sunrise. An hour-long circumnavigation of the crater is usually part of the journey. Routes from the foot of the mountain are becoming more popular and feature shrines and teahouses along the way, but you'll need two extra days to complete the journey. To avoid the worst of the crowds, take Slayden's advice and pick weekdays in late June or July, when many Japanese seem to think the mountain is "closed."

For More Information: Japan Guide

Kilimanjaro is totally walkable, but due to the altitude, trekkers take it slow, leaving time for acclimatization. Your week-long journey to the summit will be one of the toughest physical challenges of your life. As you pass through five climatic zones on your way up, you'll suffer from heat, cold, altitude and exhaustion. It's critical (and mandatory) to book a guided tour complete with porters and cooks. Expect to pay up to $5,000 to do it right, not including all the gear and clothing your tour company will recommend. Your ultimate reward: a sunrise visit to the Uhuru summit, where all of Africa spreads out before you. The best times to go are January through March and September through October.

For more information: Climbing Kilimanjaro and Tanzania Odyssey

The tallest mountain in the Western Hemisphere isn't Mt. McKinley, it's Argentina's Cerro Aconcagua, an Andean peak that's also the tallest mountain in the Southern Hemisphere. Amazingly, though, non-technical climbers who are in good shape can easily make it to the top on a guided trek (about $4,000) that typically takes three weeks from arrival in Argentina to departure. The usual route, from the north via the Vacas Valley, passes through Aconcagua Provincial Park, where glaciers and dramatic peaks and valleys abound. The final push starts from a base camp at 14,340 feet that offers meal tents, showers, even internet access. Look for a tour that includes time for several summit attempts, since bad weather and wind near the top can pin down climbers for days at a time. Most treks set off during the South American summer: January and February.

For more information: Natural High Alpine

The May 19, 1980, eruption of Mount St. Helens turned an impressive swath of southwest Washington state into a moonscape. A generation later, nature has rebounded and the mountain is slowly but surely rebuilding itself as lava pushes up from the center of the earth. From the Climbers Bivouac, it's a five-mile hike to the crater's rim. The round trip can take from seven to 12 hours, so it's best to set out early in the day, especially in the peak summer climbing season. A $22 permit is required to climb from April 1 through October 31, and the number of permits is limited in the summer months, so plan in advance. "This is a really dusty, ashy climb in the summer," says Greg Slayden. "It's better when there's snow on the slopes and you can slide down on your butt or your feet or even ski down."

For more information: U.S. Forest Service

The drama of Haleakala isn't in the ascent. After all, you can drive all the way to the top, covering 10,000 vertical feet in 38 miles. Once there, however, numerous hikes will give you an amazing view into the massive caldera that's seven miles long, two miles wide and 2,600 feet deep. Hikers at the summit also enjoy the Skyline Trail, a 6.8-mile walk that on a clear day offers sweeping views all the way to neighboring Hawaiian islands. Another walk, to the amazingly named Ka Luu o Ka Oo cinder cone, takes about half a day. For a real thrill, rent a bike and coast all the way from the summit back down to the ocean. Imagine riding a bike 40 miles through paradise without having to pedal. Sounds like a fun afternoon.

For more information: National Park Service

A two-day adventure to Kinabalu (guides are mandatory) is the world's most accessible tropical mountain climb. You begin in a cool cloud forest, keeping your eyes open for 800 species of orchids and 600 types of ferns, not to mention the area's unique, insect-eating pitcher plants. The first part of the hike starts at Kinabalu Park headquarters at 5,128 feet and rises to the well-equipped Laban Rata hut and rest stop at 10,800 feet. The next day, it's a two- to four-hour final push to the summit at Low's Peak. "It's easy, little more than a walk," says Greg Slayden. The return hike takes about five hours.

For more information: Endemic Guides

As the only 14,000-foot peak within Colorado's Rocky Mountain National Park, the easily accessed Longs Peak is popular with day climbers. A pre-dawn departure along the 7.5-mile Keyhole Route will get you to the summit in time to enjoy the view and return to the tree line before the frequent afternoon storms (during summer) arrive. You'll climb 5,000 vertical feet on your way to the broad, flat summit; exhaustion and altitude sickness may kick in if you overexert yourself. "There's so much great terrain in the Rockies," says Greg Slayden. "This is a good peak because it can force scramblers to push their limits a little bit."

For more information: National Park Service

One of the most photographed mountains in the world, Huayna Picchu is the rounded mountain rising dramatically behind the ruins of Machu Picchu. Although at first glance it looks nearly vertical and utterly unclimbable, but it's actually quite accessible. Each day, hundreds of climbers sign up to tackle its exhausting series of switchbacks, stairs and ladders. (Get there by 8 a.m. to avoid crowds.) After 90 minutes of huffing and puffing—and a few crawls through short but slightly claustrophobic caves—you emerge on the small, boulder-strewn summit. The view is unforgettable—jagged Andean peaks in the distance and the entire Machu Picchu complex some 1,200 feet straight down.

For more information: VirtualTourist.com

California's Mt. Whitney is the highest mountain in the contiguous 48 states and the crowning glory of the Sierra Nevada range. During the summer season, the popular "regular trail" from the Whitney Portal parking lot will take you on a seven-hour journey to the summit. Some hardcore trekkers grumble that this trail is actually too easy, graded so flat and with so many switchbacks that it's longer (at 10.5 miles) than it needs to be. Nevertheless, the scenery is stunning, especially during sunrise hours as you commence your trip and gaze up at the peaks glowing red and orange. You must acquire a permit via lottery to hike the regular trail during the summer.

For more information: U.S. Forest Service

"A world-class day hike, my favorite part of the Appalachian Trail," says hiking guidebook author Tom Stienstra of the daunting climb up Mt. Katahdin. "The views are nothing short of spectacular." Thru-hiker Brian Robinson is partial to the notoriously steep Abol trail. Hike in September and October to gaze at brilliant fall foliage. While crossing the vast forest, be prepared for the company of moose, bears and bobcats.

Recommended by: Jeffrey Hunter, Roy Robinson, Brian Robinson, Tom Stienstra

For more information: Baxter State Park

Making your way through Coyote Gulch feels a little like traversing a canyon on Mars. "The red rock is just incredible," says hiking columnist Kevin Myatt. "An otherwordly landscape. If you live in the east, it's something totally different." Enveloping walls; natural bridges, domes, arches; lengthy narrows; and panoramic views turn this landscape into a hiking funhouse. A popular day hike: Walking the two miles from Fortymile Ridge to Crack-in-the-Wall.

Recommended by: Kevin Myatt, Brian Robinson

For more information: Escalante Subdistrict

"Very, very unique," says Jeffrey Hunter, describing this ecological wonderland. The wildlife is abundant, and includes alligators, turtles and snakes. A 2.25-mile raised boardwalk leads you through five different environments, including forest and marsh. "Phenomenal birdwatching," says Hunter; dozens of rare species inhabit the area. As for the flora, expect "amazing orchids growing right off the trail." Not to mention ancient bald cypress trees, ferns, wildflowers and swamp lilies.

Recommended by: Jeffrey Hunter

For more information: Corkscrew Swamp Sanctuary

"A western-like landscape unlike anything I've encountered in the East," gushes Kevin Myatt of this wonderland of waterfalls, forests, rock outcroppings and panoramic views. The American Hiking Society's Ivan Levin compares the area to the Scottish Highlands. Two highlights: roaming wild ponies and blooming rhododendron. The nine short hiking-only trails rate moderate to difficult. You can also pick up the Appalachian Trail to nearby Mt. Rogers.

Recommended by: Kevin Myatt, Ivan Levin

For more information: Grayson Highlands State Park

"I hesitate to recommend it, because people will go there," admits outdoors journalist George Lauer of this famously isolated stretch of Northern California coastline. Where Highway 1 dares not continue, hikers can—through unspoiled, rugged wilderness. From scrambling along wet beach rocks while fighting pelting wind and rain, to climbing, descending, then re-climbing a cumulative 8,000 feet, the daunting 25-mile north Lost Coast Trail will motivate any hiker.

Recommended by: George Lauer

For more information: King Range National Conservation Area

These mountain peaks, two of the most photographed in North America, poke the sky at 14,000 feet. "Breathtaking," says Doug Vieira of the National Recreation and Parks Association. He loves hiking the glacial valleys and alpine lakes, then relaxing at dinner in nearby Aspen. "Even the shorter trails require (steep) elevation gains," says Margie Cohen in admiration. Try the Maroon Creek or Maroon Lake Scenic Trails for more leisurely exploring.

Recommended by: Doug Vieira, Margie Cohen

An avalanche and volcanic eruption knocked off the top of this mountain in 1980. Tom Stienstra calls the aftermath of this cataclysm the best day hike in North America. Difficult trails on the east side take you smack through the blast area to the summit's crater. "From the rim, you look down into steaming bowels of earth," he says. "You can hike all over North America and not have that experience."

Recommended by: Tom Stienstra

For more information: Mt. St Helens

"Just stunning" says Margie Cohen. "Very spectacular," agrees well-known hiker Roy Robinson. Sportswriter Bob Padecky calls the 11-mile Kalalau Trail the most memorable hike he's ever taken. "First you're in desert-like conditions, the Pacific a thousand feet below. Sand, unsurpassed vistas. Then, literally, you take a step and you're in a tropical rain forest." The hike also follows the coast through looming cliffs, lush valleys, rolling hills, and waterfalls.

Recommended by: Bob Padecky, Margie Cohen, Roy Robinson

For more information: Na Pali Coast State Wilderness Park

Yearning to go even deeper into the wild? Try this largest of U.S. national parks. Giant glaciers, abandoned mining sites, icy rivers, waterfalls, spectacular mountain vistas, grizzly bears, 9 of the 16 highest U.S. peaks, and maybe even some auroral displays await. "Some hikes are not for the feint of heart," warns Margie Cohen. Though you'll also find some moderate treks and an easy 1.5-mile jaunt right alongside a glacier.

Recommended by: Margie Cohen

For more information: Wrangell St. Elias National Park

Brian Robinson pegs this iconic trail as his favorite day hike. Of the nearly one-mile climb up, the last 400 feet are the hardest: Two steel cables lodged into the granite aid the final ascent. "It's like climbing the side of a building," Robinson says. The pay-off? A panorama of the entire Yosemite Valley and the Sierras. Says Robinson: "On a very clear day, the view is almost endless."

Recommended by: Brian Robinson

For more information: Yosemite National Park