Mammoth Cave National Park is the world's largest cave system. Located in the state of Kentucky in the United States, the park contains more than 360 miles (579 km) of cave passageways, making it twice as large as the next largest cave system, Jewel Cave National Monument which is located in South Dakota. Mammoth Cave was named a national park in 1941 and a World Heritage Site in 1981.
Encompassing more than 52,000 acres (about 21,044 hectares), the park is surrounded by the Green River. Two other rivers, the River Styx and Echo River, are underground rivers in the park. Mammoth Cave National Park is alive with wildlife, including five species of bats, two genera of crickets, cave salamanders, and cave shrimp. In addition to spelunking, visitors can enjoy hiking, camping, birdwatching, canoeing, and fishing.
The National Park Service hosts many cave tours for visitors through the Mammoth Cave National Park. A wide variety of lighted cave tours that range from one to six hours can be arranged. The two-hour Frozen Niagara tour, for example, may be a good introduction for first-time visitors. The hike is just under 1 mile (about 1.6 kilometers) and takes explorers through deep pits and high domes along a dry passageway. The Grand Avenue tour is a strenuous 4-mile (about 6.4-kilometer) hike, including 670 stairs, that may be best for experienced hikers. Other tour options include those that are lit not electrically but by paraffin lamps which visitors carry, and wild tours which give more adventurous visitors the option to venture into dusty tunnels and muddy crawlspaces.
Mammoth Cave National Park is open year-round and different tours and activities are offered at different times of the year. Reservations for tours, especially some of the longer ones, are recommended. Reservation and tour price information can be found at the Mammoth Cave National Park website. Though the cave itself is not handicap accessible, the park offers accessible trails, camping, and other activities.
Historians believe that humans have had some contact with the park for the past 6,000 years. Researchers and geologists have uncovered Native American remains in Mammoth Cave National Park and other caves in the area. Most of the remains showed signs of intentional burial; some remains led researchers to believe that there were some pre-Columbian funeral practices at work many years ago within the park.