Katmai National Park, AK
With the onset of milder temps, plants coming into full bloom, and the brown-bear population congregating to feast on salmon, spring and summer are prime tourism seasons for Katmai National Park. More than 2,000 brown bears populate this southwest Alaskan wilderness, and visitors flock to the riverbanks to watch the massive animals catch their dinner. True, the salmon run peaks in July—but so do the tourists. Do yourself a favor: Visit in June and get ahead of the pack.

Goosenecks State Park, UT
Staring into the 1,000-foot-deep belly of Goosenecks State Park in southeastern Utah is like peeling back layers of geologic time. Carved over a period of 300 million years by the steady grind of the silt-laden San Juan River, which empties into Lake Powell, Goosenecks’ deep canyons are a place to stand still and get some perspective. The park's primitive set-up keeps most visitors day-tripping, so pack lots of extra water and camp overnight for a spectacular, solitary sunrise to start your day right.

Cumberland Island National Seashore, GA
Part of the National Park Service’s protected lands, Georgia’s Cumberland Island is one of the most pristine places in America’s coastal region. Nearly half of the island’s 36,415 acres are marsh, mudflats, and tidal creeks known for their sea turtle, wild turkey, armadillo, shore bird, and wild horse inhabitants. The park also offers 50 miles of hiking trails, trout and bass fishing, road biking, and marsh kayaking. Tip: Cumberland Island is accessible only by water, and ferry-boat reservations are recommended in summer months.

Theodore Roosevelt National Park, ND
Theodore Roosevelt National Park, located in the heart of the North Dakota badlands, is named for the man who established a number of national forests and refuges during his presidency. Fascinated by the desolate beauty of the area, Roosevelt once wrote, “I would not have been President, had it not been for my experience in North Dakota.” You owe it to yourself to experience the beauty that inspired such a proclamation.

Columbia River Gorge National Recreation Area, OR
Green, clean, friendly, and vibrant. Take a true walk on the wild side across 5,000 rugged acres and 70 miles of trails in the nation's largest urban wilderness, Forest Park in Portland, Oregon. Minutes away, you'll discover the Columbia River Gorge, where 77 brilliant waterfalls tumble from the glaciers and snowfields of Mount Hood.

Huanglong (Yellow Dragon) Scenic Area, Sichuan Province, China
Yellow Dragon's valley is veiled in calcium-carbonate sediment, creating the illusion of a golden dragon winding its way through a ravine. The park's 270 square miles also boast snow-covered peaks, waterfalls, gorges, and hot springs. It gained UNESCO World Heritage status in 1992 for its abundant forest ecosystems and population of endangered animals, including the giant panda and the Sichuan golden snub-nosed monkey. The rainy season starts in July, which is also the start of peak tourist season. Visit in June, when nights may still be cold, but crowds won't be a factor.

Glacier-Waterton Lakes International Peace Park, MT & Alberta
In 1932, the U.S. and Canadian governments made Montana’s Glacier National Park and Alberta’s Waterton Lakes National Park the world's first International Peace Park, symbolizing the goodwill between the United States and Canada. Hike through spring-irrigated prairies, take in ancient glaciers, and climb craggy alpine peaks (they'll likely still have some snow in June). Keep your eyes peeled for mountain lions, wolves, bears, and a host of other wildlife along the way.

Manu Biosphere Reserve, Peru
Stretching from the arid forests of upper Andes to the tropical Amazon rainforest, the 5.5-milion-acre Manu Biosphere Reserve contains startlingly diverse landscapes. But even more incredible than the geographical diversity, the Biosphere Reserve now has the highest concentration of avian life in the world: more than 1,000 different species have been recorded thus far (including seven different species of macaws). The 178-mile trip from Cuzco can often take two days but is worth the effort, as you'll explore unpaved roads alongside Inca ruins, cloud forests, and lush, lowland rainforest.

Gifford Pinchot National Forest, WA
The Gifford Pinchot National Forest sits at the very core of the Pacific Northwest's volcanic cauldron and is home to the eruption-prone Mount St. Helens. No other forest exhibits such an intense concentration of craters, lava fields, volcanic caves, lava tubes, and pumice pits. The forest's many moonscapes are surrounded by wilderness, boasting thick stands of mountain hemlock and old-growth Douglas fir. Let the Pacific Crest Trail guide you through this inspiring park, or get a permit to climb 8,364-foot Mount St. Helens for uninterrupted views of the Cascades.

Adirondack State Park, NY
Adirondack Park is the largest park of any kind in the Lower 48, larger than Yellowstone, Yosemite, the Grand Canyon, and Olympic national parks combined. Its six million acres contain more than 2,800 ponds and lakes and 1,500 miles of river. Indeed, 90 percent of all plants and animals that exist north of the Mason-Dixon Line and east of the Mississippi River can be found in the Adirondacks.