National Parks Turn 100: Photos

The National Park Service turns 100 on Aug. 25 and from then til Aug. 28 you can visit any of the more than 400 national parks around the country for free. Here we've collected some of our favorite National Park spots, which are featured in the 3-D IMAX film, National Parks Adventure.

Above: Half Dome in Yosemite National Park. First protected in 1864, the park is best known for its waterfalls, deep valleys, grand meadows, ancient giant sequoias, a vast wilderness area and the Sierra Nevada mountain range.

Along 40 miles of the Lake Superior shoreline -- the largest, deepest, coldest and most pristine of all the Great Lakes -- Pictured Rocks National Lakeshore contains sandstone cliffs, beaches, sand dunes, waterfalls, lakes, winter ice formations and forests. It's a frequent destination for adventurers, with year-round opportunities for hiking, camping, climbing and sightseeing. Above: Conrad Anker climbs frozen waterfalls in Pictured Rocks.

Above, the sun rises over Crater Lake National Park in Southern Oregon. The deep, blue lake is surrounded by sheer cliffs that are thousands of feet high and features two beautiful islands and a violent, volcanic past.

Grand Teton National Park is rich with extraordinary wildlife, clear glacial lakes and alpine terrain. It contains more than 200 miles of trails, boating on the Snake River, and unmatched natural serenity. Visitors can see rare rock formations, huge glaciers, moose, bears and flora such as the majestic white pine. Above: Sunrise reflects on Jackson Lake in Wyoming.

Glacier National Park is a vista of forests, alpine meadows, rugged mountains and lakes. Glacier has over 700 miles of trails and a deep Native American history. Above, the sky and mountains reflect on St. Mary's Lake in Montana.

Climbers reach the top of the Three Penguins in Arches National Park, Utah. Arches is a celebration of color, landforms and textures unlike any other in the world. The park has over 2,000 natural stone arches, in addition to hundreds of soaring pinnacles, massive fins and giant balanced rocks.

Brown bears catch salmon in Katmai National Park and Preserve in Alaska. The national monument was established in 1918 to protect the volcanically devastated region surrounding Mount Katmai and the Valley of Ten Thousand Smokes. Today the park remains an active volcanic landscape, but it also protects 9,000 years of human history as well as important habitat for salmon and thousands of brown bears.

The Grand Canyon is 277 river miles long, 18 miles wide and a mile deep. The immense canyon offers unique geologic color and erosional landforms, carved by the Colorado River.

Giant sequoia trees grow in Mariposa Grove in Yosemite National Park, Calif.

Steam rises from the Sapphire Pool in Biscuit Basin in Yellowstone National Park in Wyoming. Yellowstone was the first U.S. National Park, established in 1872. The park contains the majority of the world's geysers. And the surrounding mountain wilderness is home to grizzly bears, wolves, herds of bison and elk. The park is the one of the last, nearly intact temperate ecosystems.

The Great Fountain Geyser erupts in Yellowstone National Park, Wyo.

Mesa Arch overlooks Canyonlands National Park in Utah, a maze of canyons and buttes carved by the Colorado River. The park is divided into districts: Island in the Sky, The Needles, The Maze, Horseshoe Canyon Unit and The Rivers. Each shares a primitive desert atmosphere, but offers different opportunities for sightseeing and adventure.