The National Park Service manages nearly 400 national parks, which serve more than 275 million visitors a year. If visiting one or more is on your resolution list for the year, here's a rundown to help you decide where to go.

• Yellowstone National Park: Established in March of 1872, Yellowstone National Park lays claim to being the first national park in the United States. The park straddles Wyoming, Montana and Idaho, and within its borders it's known for varying geography, diverse wildlife and a host of active geothermal areas (such as the famous geyser, Old Faithful).

• Carlsbad Caverns National Park: The striking rock formations of Carlsbad Caverns are located underneath the Guadalupe Mountains of southeastern New Mexico. The park includes the third largest cave chamber in the United States, and chambers continue to be discovered and explored.

• Grand Canyon National Park: Carved into the land by the Colorado River over millions of years, the Grand Canyon was first declared a national park by President Theodore Roosevelt in 1919. Since then, the park has attracted about 5 million visitors every year for its sightseeing, hiking, whitewater rafting and helicopter tours.

• Mammoth Cave National Park: As the longest cave system known in the world, it's no wonder Mammoth Cave was established as a national park. The Kentucky cave has 365 miles of passageways, and it's widely believed that many more miles have yet to be discovered.

• Mesa Verde National Park: Mesa Verde, or "Green Table" in Spanish, offers visitors a unique experience to see the ruins of homes and villages constructed by the Anasazi, the ancient Pueblo people, almost 800 years ago. Carved into caves and outcroppings, these spectacular cliff dwellings in Colorado became federally protected as concerns grew over the deteriorating conditions of the ruins.

• Olympic National Park: Consisting of the Olympic Mountains, the Pacific coastline and the surrounding temperate forests, Olympic National Park was declared a national park in 1938 by President Franklin Roosevelt. In addition to hiking, skiing and rafting, backpacking along the beach is a popular activity in the park as the length of the coastline is perfect for multi-day trips.