Insider Tip: Since parking is limited at the trailhead and summer days are very hot, get an early start for this hike.

See our Arches National Park Guide

Olympic National Park, Washington

Photograph by Edmund Lowe, Alamy

Hoh River Trail

Round-Trip: 6.2 miles, When to Go: Year-round, Level: Easy

The Hoh Rain Forest on the west side of Olympic National Park preserves one of the finest temperate rain forests in the U.S., a place that gets up to 14 feet of rain a year. This hike plunges right into its deep, mossy, densely forested core. Though it parallels and flirts with the Hoh River, this mostly level trail remains mainly beneath the canopy of massive old-growth trees—bigleaf maple, western hemlock, Sitka spruce, and Douglas fir. Fallen giants serve as “nurse logs” to saplings. Giant ferns rise from the soft forest floor. The air feels superoxygenated. But for the sound of the river and perhaps some rain tapping on leaves, a hush prevails here.

Insider Tip: The trail continues 17.6 miles to Glacier Meadows, trailhead for an ascent of Mount Olympus. You can hike as far as you wish, but try to make it at least 3.1 miles, where an unmarked spot known as One Square Inch of Silence is considered by preservationists to be the quietest place in America.

See our Olympic National Park Guide

Wrangell-St. Elias National Park

Photograph by Ethan Welty, Tandem

Root Glacier Trail

Round-Trip: 4 miles, When to Go: Summer, Level: Easy

This hike in the heart of the country’s largest national park is quintessentially Alaskan. It brings you up close to majesty—a magnificent glacier with a mountainous backdrop—and history, in the form of mining ruins along the way. From McCarthy, take a shuttle to Kennecott and start the hike in Kennecott Mill Town. The trail heads north, crosses over Bonanza Creek, then traverses the lateral moraines of the Kennicott and Root Glaciers before reaching Root Glacier. Proceed very cautiously; you really need crampons to get to the heart of the glacier.

Insider Tip: Local outfitters lead guided hikes with crampons if you desire the full glacier experience—beautiful blue pools, sculpted concavities of ice, and cascading waterfalls. The park has information.

See our Wrangell-St. Elias National Park Guide

Mammoth Cave National Park, Kentucky

Photograph by Clint Farlinger, Alamy

Wild Cave Tour

Round-Trip: 5 miles, When to Go: Year-round, Level: Strenuous

Most cave tours are sedate affairs, floodlit with mood lighting and gussied up with amenities such as stairways and handrails. Not so Mammoth Cave’s Wild Cave Tour, where you’ll slither through crawlways—with names like Birth Canal and No Name Pass—so narrow that your boots have to go through sideways. (If your chest or hip measurement exceeds 42 inches, you’re steered to a more conventional tour.) Figure also on some hands-and-knees crawling, crouched duckwalking, free climbing, and plenty of upright walking deep inside the world’s longest cave system. It’s a six-hour challenge, but the reward is hard-earned looks at astounding limestone formations—for instance, the series of monumental domes called Cathedral Domes—that most people will never get close to.

Insider Tip: The Park Service provides outerwear, knee pads, helmets, and headlamps, but you’ll need ankle-high boots and a change of clothes and footwear.

See our Mammoth Cave National Park Guide

Grand Teton National Park, Wyoming

Photograph by Niebrugge Images/Alamy

Cascade Canyon Trail to Lake Solitude

Round-Trip: 14.4 miles, When to Go: Summer and fall, Level: Moderate

The magnificence of Grand Teton National Park is in full display when you hike west from Jenny Lake up Cascade Canyon. A half mile into the hike is Hidden Falls; a half mile later is Inspiration Point and a wonderful view down to Jenny Lake and the mountains that frame Jackson Hole. Look to the west and you see the Cathedral Group—Grand Teton, Mount Owen, and Teewinot—towering above you like church spires. As you press on, the crowds diminish, and you’re likely to see moose grazing diffidently to the side of the trail. Though you can turn back anytime and have a great hike, Lake Solitude at the end of the trail is a superb reward. There you see the sheer rock face of Grand Teton and an open bowl spangled with glacier lilies, mountain lilies, and pink sticky geraniums.

Insider Tip: Save two miles of hiking by taking the shuttle boat across Jenny Lake and begin your hike from the west shore.

See our Grand Teton National Park Guide

Haleakalā National Park, Hawaii

Photograph by John Hoover, Photo Resource Hawaii/Alamy

Halemau'u Trail

Round-Trip: 7.4 miles, When to Go: Year-round, Level: Moderate

Perhaps you've heard it before, but hiking on the Halemau'u Trail is like hiking on Mars. The otherworldly quality of this dramatic, 1,400-foot plunge to the floor of Haleakalā's crater is part of its thrill. Before leaving Earth you pass through native scrub forest that looks exactly as it did 2,000 years ago—a rarity in Hawaii, which has been overrun by non-native species. At Crater Rim Overlook, behold a dizzying view across the mountain’s northern slopes to lush sea cliffs far below. Mars is next: You switchback down a barren slope of red and black cinder cones, bereft of vegetation, until you reach Holua Cabin—a reasonable turnaround point for this extraterrestrial voyage.

Insider Tip: Watch for natives along the way: pueo, a little owl, and nēnē, Hawaii’s endemic goose and state bird.

See our Haleakalā National Park Guide

Redwood National Park, California

Photograph by Fabian Gonzales, Alamy

James Irvine/Miners Ridge Loop

Round-Trip: 11.6 miles, When to Go: Spring through fall, Level: Moderate

When you hike in the presence of the world’s tallest living things, a mist rising toward their distant canopy, the forest carpeted in large ferns and redwood clover, it’s easy to get lost in reverie—or simply awe. This hike traces ridge after ridge of magnificent 300-foot-tall coast redwoods, yet offers even more. It also does a stint along the coast at Gold Bluff Beach, crosses coastal meadows where Roosevelt elk graze, and passes through Fern Canyon. There you enter a primordial world—a narrow cleft with 30-foot walls draped with giant, ancient fronds, including unusual five-fingered ferns.

Insider Tip: Ancestry of the ferns in Fern Canyon can be traced back 325 million years, so it was only fitting that the canyon served as a setting for the film Jurassic Park 2.

See our Redwood National Park Guide

Yellowstone National Park, Wyoming

Photograph by Raymond Gehman, National Geographic

Mount Washburn from Dunraven Pass Picnic Area

Round-Trip: 7.2 miles, When to Go: Summer and fall, Level: Moderate

Wildflowers and wildlife are just two of the glories of this hike to the top of 10,423-foot Mount Washburn. In July and August in particular you’ll catch a great show of mountain flowers, and with an early start, have a chance of spotting peregrine falcons, elk, mule deer, and—near the top—bighorn sheep. But this classic hike, a must-do that many do over and over as a virtual pilgrimage, is really about the views. As you pass in and out of forest you get some fine vistas, but the jaw-dropper is from the summit, site of a still operating fire lookout. All of Yellowstone and more lies before you—Yellowstone Lake, Hayden Valley, the Absaroka and Beartooth Ranges, even the distant Grand Tetons. Allow time to linger.

Insider Tip: Looking south with a geological mind-set, you can imagine the giant Yellowstone Caldera, a supervolcano, that spreads over a 34- by 45-mile area containing the park’s famous hot spots.

See our Yellowstone National Park Guide

Zion National Park, Utah

Photograph by Ruaridh Stewart; ZUMA Press/Corbis

Zion Narrows

Round-Trip: 16 miles, When to Go: Summer and early fall, Level: Moderate

This hike starts with a brief paved section called Riverside Walk. After that, you'll need some old running shoes or sturdy sport sandals when you start sloshing your way up the chilly North Fork of the Virgin River between 2,000-foot vertical walls of orange-red sandstone. The hike proceeds upstream from the Temple of Sinawava and continues as far as you wish; Orderville Canyon, in the heart of the Narrows, is a common turnaround. Every twist of the river reveals subtleties of the walls, which occasionally constrict the canyon to a mere 20 or 30 feet across. Marvel at the sunset colors in striations of sedimentation, and don’t forget to look up at tributary streams tumbling down from side canyons.

Insider Tip: Late summer thunderstorms can create flash-flood conditions, so be sure to check with the visitor center before setting out. Pack your things inside Ziploc bags, and use hiking poles for extra balance.

See our Zion National Park Guide

Glacier National Park, Montana

Photograph by Gordon Wiltsie, National Geographic

Highline Trail

One-Way: 11.5 miles, When to Go: Summer, Level: Moderate

Glacier’s fabled Highline Trail from Logan Pass Visitor Center to the Loop on Going-to-the-Sun Road embodies all the wild, treeless glory of the park’s high country—soaring peaks and ostentatious wildflowers, plus the possibility of spotting mountain goats, bighorn sheep, and bears. Although the hike follows the course of the Continental Divide, it’s surprisingly easy—mainly because it remains a merciful 2,000 feet beneath the Divide’s serrated summits (and, thanks to the park shuttle, you don’t have to retrace your steps). Midway, take the 0.8-mile Grinnell Glacier Overlook Spur for a high view of the rapidly retreating glacier. Then pause for a cold drink at historic backcountry Granite Park Chalet before dropping down to the Loop trailhead on Going-to-the-Sun Road for a shuttle ride back.

Insider Tip: Highline Trail is typically not free of snow until mid- to late July.

See our Glacier National Park Guide

Black Canyon of the Gunnison National Park,

Colorado

Photograph by Kennan Harvey, Aurora/Alamy

North Vista Trail to Exclamation Point Overlook

Round-Trip: 3 miles, When to Go: Spring through fall, Level: Moderate

Other canyons may be more grand, but few match Black Canyon for its combination of sheer walls, narrow opening, and take-your-breath-away depth. The rims of the 2,000-foot gorge are just 500 feet apart in sections. The North Vista Trail starts at the North Rim Ranger Station and leads to an astounding overlook called Exclamation Point, perched 1,900 feet above a bend in the Gunnison River. You can look down into the gorge in two directions. The ambitious can continue to Green Mountain, 867 feet higher (a seven-mile round trip), for an aerial view of both rim and canyon, as well as the San Juan and West Elk Mountains beyond.

Insider Tip: No trails lead to the canyon floor, but the determined can scramble down SOB Draw (just east of the North Rim Campground) for some superb trout fishing in the Gunnison. The climb back out is very strenuous.

See our Black Canyon of the Gunnison National Park Guide

Mount Rainier National Park, Washington

Photograph by Zach Holmes, Alamy

Summerland Trail

Round-Trip: 8.4 miles, When to Go: Summer, Level: Moderate

As grand as the summit of 14,410-foot Mount Rainier may be, a subalpine meadow at 6,000 feet on its eastern flank is every bit as spectacular in its own way—particularly if you enjoy a dazzling show of wildflowers. This hike starts at Fryingpan Creek trailhead and climbs alongside glacier-fed Fryingpan Creek through old-growth forest, then steepens before reaching a valley where clear-day views of mighty Rainier open up. Another half mile puts you onto Summerland Meadow and a glorious show of lupine, Indian paintbrush, and avalanche lilies. People tend to toss out Heidi and Sound of Music allusions here, but the reality is even grander.

Insider Tip: Watch for mountain goats and herds of elk, though you might have to settle for omnipresent marmots.

See our Mount Rainier National Park Guide

Sequoia and Kings Canyon National Park,

California

Photograph by Sarah Lee, Redux

Lakes Trail to the Watchtower

Round-Trip: 7 miles, When to Go: Summer and fall, Level: Moderate

The start of this gradually rising hike through mixed conifers is pleasant enough, but when it breaks out of the woods, it becomes stunning. As you approach the Watchtower—a granite prominence high above the Marble Fork of the Kaweah River—you get a bird’s-eye view of 1,200-foot Tokopah Falls. Then, from the Watchtower itself, you take in the grandeur of the High Sierra—the canyon of the Kaweah, the soaring peaks of the Great Western Divide beyond, and far below, the forests you traversed to get there.

Insider Tip: On the way to Wolverton Picnic Area, trailhead for this hike, are trails that lead past the park’s famous giant sequoias, including the massive General Sherman Tree, 275 feet tall and 36.5 feet in diameter.

See our Sequoia and Kings National Park Guide

Canyonlands National Park, Utah

Photograph by Keith Kapple, Alamy

Elephant Hill to Druid Arch

Round-Trip: 10 miles, When to Go: Year-round, Level: Moderate

Canyonlands has a wondrous collections of rock formations, including spires, needles, and arches, and this hike from Elephant Hill picnic area has them all—including one of the park’s signature formations, Druid Arch. To get there, you pass through Elephant Canyon, where you’re surrounded by countless pillars of Cedar Mesa sandstone banded in hues of orange and white. Just before the arch, you can see 50 miles north to Candlestick Tower. Then Druid comes into view, rising dramatically above the rim of the canyon like a giant red megalith. A tough scramble leads to the mesa at its base.

Insider Tip: Go very early in the morning for the best light. Map notes: It’s in the park’s Needles District. Elephant Hill is west of Squaw Flat Campground, and the trail proceeds south through Elephant Canyon.

See our Canyonlands National Park Guide

Rocky Mountain National Park, Colorado

Photograph by Rich Crowder, Aurora

Bear Lake to Fern Lake Loop

Round-Trip: 9 miles, When to Go: Summer to mid-fall, Level: Moderate

This slice-of-heaven hike in the heart of the park has everything you can dream of in a Rocky Mountain hike. You climb beside streams, pass roaring waterfalls and massive boulders, hike through forests and reach high, trout-filled lakes—all beneath towering peaks. From the trailhead at Bear Lake, you make a long steady climb before reaching Odessa Lake, then dropping to Fern Lake, both nestled below Little Matterhorn (11,586 feet), Knobtop (12,331), and Gabletop (11,939) Mountains. As you complete the open loop, you pass by Marguerite Falls, Fern Falls, and the Pool—a swirling rock-walled water pocket beneath the confluence of Spruce and Fern Creeks with the Big Thompson River. You’ll follow the Big Thompson out to the Fern Lake Trailhead.

Insider Tip: The park’s free shuttle service makes this open loop easy. Take the shuttle from Moraine Visitor Center to the trailhead at Bear Lake, do the hike, and meet it again at Fern Lake Trailhead.

See our Rocky Mountain National Park Guide

Shenandoah National Park, Virginia

Photograph by Pat & Chuck Blackley, Alamy

Hawksbill Loop

Round-Trip: 2.9 miles, When to Go: Spring through fall, Level: Moderate

One of the beauties of Shenandoah’s Skyline Drive is the access it provides to great hikes and high points in the park. In the case of this loop, it’s both a great hike and the highest point in the park: Hawksbill, at 4,050 feet. Start at the Hawksbill Gap parking area (mile marker 45.6) and follow the Appalachian Trail (white blazes) to the Salamander Trail (blue blazes) and switchback up to the summit. Watch for deer, grouse, and peregrine falcons. From the Appalachian Trail you occasionally break out of the oak/hickory forest for views down into the Shenandoah Valley. And from the stone platform atop the summit you see the world—endless ridges cloaked in forest, defined by hollows and valleys—and the distinctive rocky outline of Old Rag looming off to the east. Return by way of the Lower Hawksbill Trail.

Insider Tip: If it’s windy at the top, the Byrd’s Nest Shelter below the summit provides a protected spot for a picnic.

See our Shenandoah National Park Guide

Acadia National Park, Maine

Photograph by Jose Azel, Aurora

Precipice Trail

Round-Trip: 1.8 miles, When to Go: Summer and fall, Level: Strenuous

The Precipice Trail is not a technical climb, but nor is it for the faint of heart. For the willing, it’s great fun with an amazing payoff. From the trailhead on Park Loop Road, it starts with what feels like a vertical ascent of a thousand-foot granite dome on Champlain Mountain. Judiciously placed iron rungs and rings get you up the dicier bits. Then you’ll need to do a bit of boulder hopping and scrambling to reach the viewpoint on top. And what a view: Before you is the entire east side of Mount Desert Island with its ponds, puddles, meadows, mountains, cliffs, and offshore islets.

Insider Tip: The trail is generally closed early in the summer to protect nesting peregrine falcons. Check with the park.

See our Acadia National Park Guide

Great Smoky Mountains National Park,

North Carolina and Tennessee

Photograph by Danita Delimont, Alamy

Mount Cammerer Loop

Round-Trip: 16 miles, When to Go: Spring through fall, Level: Strenuous

This hike takes in one of the most remote sections of the Appalachian Trail and one of the park’s best views. From Big Creek Ranger Station in the northeast part of the park, hike the Chestnut Branch Trail to the Appalachian Trail. Then it's on to 4,928-foot Mount Cammerer, where a 0.6-mile spur leads to a fire tower that’s a rock-and-wood work of art built by the Civilian Conservation Corps during the Depression. It commands a view of the east end of the park—endless ridges of forest- cloaked Smokies spreading to Tennessee and eternity. Descend by way of Big Creek Trail.

Insider Tip: On the way back, pause to cool off in any of the deep pools that lie beneath tumbling cascades along Big Creek.

See our Great Smoky Mountains National Park Guide