Top 10 National Park Activities

Snorkeling: Virgin Islands National Park

You'll want flippers, a mask and snorkel to explore the best trail in St. John because it's actually underwater. The snorkeling trail at Trunk Bay is a 225-yard swim lined with signs describing the fish, coral and plants that live in the warm turquoise waters. After exploring the sea, relax on the crescent-shaped beach and appreciate the scenery at one of the country's most idyllic national parks.

Orienteering: Prince William Forest Park

Set off on a modern-day treasure hunt at Prince William Forest Park. Leave the GPS system at home for an orienteering adventure using just a map and compass to follow clues around one of the park's 30 courses. You can choose to set your own pace, whether it's a slowpoke family stroll while the kids master the compass or a competitive jaunt to race to the final clue.

Hiking: Great Smoky Mountains National Park

Hikers can set off on a great adventure on foot any time of year in the Great Smoky Mountains National Park. With more than 800 miles of trails, there are plenty of options including scenic strolls through fields of wildflowers and strenuous climbs to the top of the park's glorious waterfalls. A popular day-hike is a strenuous 8-mile trip to Charles Bunion along the Appalachian Trail. The 3-mile trip to Baskins Creek Falls follows an accessible trail with footbridge crossings to a 25-foot waterfall while the 8-mile roundtrip to Ramsay Cascades is a moderately strenuous trek through old-growth forest.

Horseback-Riding: Theodore Roosevelt National Park

Experience the wild badlands on a horseback ride through Theodore Roosevelt National Park. The former president galloped through these vast prairies himself in the late 19th century. The park's trail system is open to horses, and some visitors choose to ride in on their own steed. For the rest of us, Peaceful Valley Ranch organizes day-trips all summer long for riders over 7 years old.

Rafting: Grand Canyon National Park

While more than 5 million visitors head to the Grand Canyon every year, many make the mistake of simply peering out over the Rim before climbing back in the car. To truly experience the grandeur of the Grand Canyon, set off on a white-water-rafting adventure on the Colorado River. Float down smooth water on half- or full-day trips, or check out a longer excursion and spend three to 18 days riding the rapids in the shadows of the canyon's towering red walls.

Spelunking: Mammoth Cave National Park

Mammoth Cave National Park is the world's longest known cave system with spacious chambers and twisted labyrinths beneath Kentucky's Green River Valley. Serious spelunkers can descend 300 feet down 670 stairs and narrow passageways and tunnels to explore the underground rooms and hills on the Grand Avenue Tour. It takes over four hours to traverse this 4-mile-long stretch of the cave system. Lantern tours of the caves' passageways at Violet City give guests an idea of what it was like for the early cave explorers in the 1800s.

Paddling: Glacier Bay National Park

Many visitors take in Glacier Bay's snow-capped mountains and towering glaciers from the deck of a cruise ship. For a more intimate tour of the park, glide through the waters in a low-lying kayak.

Sandboarding: Great Sand Dunes National Park and Preserve

Who says you can't ski in the summer? Rocket down rolling sand dunes at Great Sand Dunes National Park and Preserve in Colorado. You'll need good equipment, such as downhill skis, a snowboard or a flat-bottomed plastic sled, to set off on a wild ride through the sand. The conditions aren't good after rain or when the weather is too dry as the sand may be too soft to pick up some speed. Sandboarding is permitted on any of the unvegetated dunes and is particularly good at the 300-foot slope near the Castle Creek Picnic Area.

Wildlife Viewing: Yellowstone National Park

Enjoy a wild safari a bit closer to home at Yellowstone National Park, home to more than 60 types of mammals and 318 species of birds. Black bears and grizzlies make their home in forests while coyotes, gray wolves and bobcats frolic in the meadows. Bison, elk and moose roam the grasslands while bighorn sheep meander along the mountainside. Bald eagles soar overhead and trumpeter swans make their nests alongside the park's rivers. Bring a pair of binoculars and a camera, and join a ranger tour to learn more about these fascinating residents.