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Yellowstone, Wyoming - Yellowstone was established in 1872 and is the oldest national park in the US.

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Yellowstone, Wyoming - A thermal wonderland of burping mud pots, bubbling fumaroles and explosive geysers.

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Yellowstone, Wyoming - The park’s boundaries also embrace craggy peaks, pristine alpine lakes and verdant forests.

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Yellowstone, Wyoming - Equally spectacular is the wildlife: bears, bison, moose, sheep and wolves.

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Arches, Utah - Shaped by wind and water over millions of years.

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Arches, Utah - Over 2,000 sandstone arches decorate the weatherworn landscape.

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Arches, Utah - Resembling rusty horseshoes, these amazing geological anomalies are the showstoppers.

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Arches, Utah - However look out for balancing boulders, bridges, and towers during one of your hikes.

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Grand Canyon, Arizona - The Grand Canyon’s awesome gorge – a mile deep and up to 18 miles wide in places – is one of the most photographed natural wonders in the world.

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Grand Canyon, Arizona - No wonder then Grand Canyon is the second most visited park in the country.

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Grand Canyon, Arizona - Visitors tend to congregate along the South Rim, so head for the tree-textured North Rim for a more exclusive experience.

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Grand Canyon, Arizona - Rafting the churning Colorado River below is on every adventure tourist’s wish list.

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Great Smokey Mountains, North Carolina/Tennessee - Welcoming around 11 million outdoor enthusiasts a year, this is the nation’s number one visited national park.

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Great Smokey Mountains, North Carolina/Tennessee - Amble through this undulating landscape in spring, and you’ll witness a spectacular display of flowering plants that carpet the valleys with flecks of color.

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Great Smokey Mountains, North Carolina/Tennessee - Arrive in fall, and the gold and copper canopy simply shimmers.

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Great Smokey Mountains, North Carolina/Tennessee - For the best views head for Clingsmans Dome, which at 6,643 ft, is the park’s highest point.

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Arcadia, Maine - Much of the park lies on Mount Desert Island, where sea and mountain meet.

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Arcadia, Maine - As one of the first places in the US to see the sunrise each morning, summer sees early bird crowds gathering before dawn on Cadillac Mountain to witness this romantic event.

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Arcadia, Maine - Hike the park’s many trails, or take to the water for an equally rewarding excursion by kayak.

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Crater Lake, Oregon - The lake in question is the deepest in the United States, sunk into the cup of an 8,000-year-old dormant volcano.

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Crater Lake, Oregon - Fed by rain and snow, the lake’s crystal blue waters mirror the Cascade Mountain Range, a favorite winter sports playground.

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Crater Lake, Oregon - The park itself is the fifth oldest in the nation, and features well-established walking and hiking trails.

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Crater Lake, Oregon - Rim Drive is the most popular road in the park, following a scenic route around the caldera rim.

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Saguaro, Arizona - Named after the nation’s largest cacti, Saguaro is the Old West personified.

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Saguaro, Arizona - Some of these majestic plants reach over 50 feet tall and last nearly 200 years.

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Saguaro, Arizona - The park is home to plenty of other cacti, including the tiny mammillaria.

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Saguaro, Arizona - Wildlife enthusiasts should look out for roadrunner (picture), the vermilion flycatcher, and the whiskered screech owl.

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Olympic, Washington - Three distinct ecosystems (mountain, rainforest and coastline) characterize the landscape here.

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Olympic, Washington - Standing in the shadow of Mount Olympus, it is frequently visited for the ancient Hoh and Quinault rainforests.

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Olympic, Washington - The unspoiled terrain is also celebrated for its resident Roosevelt elk and, along the coastline, sea lions and bald eagles.

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Glacier, Montana - Another hugely popular outdoors escape, the park showcases 25 glaciers surrounded by ice blue lakes.

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Glacier, Montana - Of these, the accessible Grinnell Glacier provides hikers with splendid peak-and-valley views.

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Glacier, Montana - If warmer weather’s more your scene, arrive in late spring for a technicolor wildflower extravaganza.

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Rocky Mountain, Colorado - Easy access to 150 lakes and 450 miles of streams, the 'roof of the world is among the ten most visited parks in the US.

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Rocky Mountain, Colorado - The park’s eye-popping vistas are accessible by foot, horseback and snowshoe, depending on the time of year.

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Rocky Mountain, Colorado - The Trail Ridge Road is 48 miles of pure magic.

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