Hikes to Keep You Fit

1. Kilauea Iki Trail, Big Island, Hawaii

No trip to the Big Island is complete without a visit to Hawai'i Volcanoes National Park, where you could stand within feet of flowing lava. Once there, drive to the Kilauea Iki trailhead for this four-mile, moderate hike. You'll descend through a lush rain forest until you pop out on the crater floor, which is still steaming. Hike your way across the crater until you spot the trailhead going back into the rain forest, now ascending. By the end, you'll have climbed up and down the equivalent of a 40-story building.

2. Cascade Canyon Trail, Jackson, Wyoming

You might come to Jackson for the Antler Arches and the Cowboy Bar, but the real draw is Grand Teton National Park. Drive to Jenny Lake and hop a ferry to hit the trail. Start off with the crowds, heading to Inspiration Point for fantastic views. Then follow Cascade Canyon Trail until it's just you, the boulders and the bears, although hopefully, you won't see any. (But do make noise to alert them of your presence.) The Tetons will lumber over you, showing off their jagged peaks, as you skirt Cascade Creek, going as far as you want before turning. An option when you get back to the start? Hike the two-plus mile trail around the lake.

3. Hanging Lake Trail, Glenwood Springs, Colorado

You can't beat Colorado hiking, and this out-and-back trail is one of the best, which is why it's often crowded. Note, though, that the park service lists this trail as difficult, as it gets steep and strenuous in spots and requires traversing some rocky areas. You'll climb over a mile, ascending about 1,000 feet. At the top, you'll find a clear, turquoise blue lake. Pack a picnic lunch and enjoy it by the lake before retracing your steps.

4. Gros Piton, Fond Gens Libre, St. Lucia

For a hike you won't ever forget, head to Gros Piton, a UNESCO World Heritage site. It's super tough (and does require a guide) so only if you're extremely fit should you think about going to the top (about two hours or longer). It's an out-and-back trail, and if you can't make it to the top -- which isn't uncommon -- the halfway point is a good turnaround, as the first half of the trail is mild. The further you climb, though, the steeper the trail gets and the more boulders you have to scramble over. The last quarter of the trail may also be slippery, so be prepared. At the top, though, you'll catch awesome views of Petit Piton, Gros Piton's sister peak and the surrounding area. You'll no doubt have spaghetti legs coming down, but hopefully, the locals will be at the bottom to sell you an ice cold Piton, the beer of St. Lucia.

To locate other great hikes, read about Backpacker Magazine's Find-A-Hike.