Half Dome is one of the biggest crowd-pleasers at California's Yosemite National Park.
Justin Sullivan/Getty Images/File
Grand Canyon National Park —
Yaki Point on the South Rim is a great place to watch the Grand Canyon change colors as the sun sets.
Courtesy Michael Quinn/National Park Service
Grand Canyon National Park —
Rafting the Colorado River through the Grand Canyon can be a day trip or up to 25 days, depending on your pleasure and how much time you have.
Courtesy Mark Lellouch/National Park Service
Yellowstone National Park —
Grand Prismatic Spring is one of the most fascinating spots at Yellowstone, which has an abundance of intriguing spots to explore. It's in Midway Geyser Basin, about 5 miles from Old Faithful. Sometimes, you can see the steam change colors because of the spring's bacteria.
Wyoming Office of Tourism
Yellowstone National Park —
Hikers should explore Yellowstone in groups of at least three, stay on designated trails, carry bear pepper spray and make noise as they hike to avoid surprising bears, rangers say.
Arches National Park —
The red coloring in the arches at the namesake Arches National Park comes from sandstone with iron oxide.
GERO BRELOER/AFP/Getty Images/File
Great Smoky Mountains National Park —
Great Smoky Mountains National Park is the most-visited national park in the country, with 9.4 million visitors in 2013.
Christine Hoyer/NPS
Great Smoky Mountains National Park —
Right after sunrise is the best time to see active wildlife at Cades Cove in Great Smoky Mountains National Park.
