40 Photos of Mammoth Cave National Park: One of Top 10 U.S. Wonders

It is also known as Mammoth Cave National Park; established in 1941. It is a beautiful cave which is considered as the longest cave system of the world. The park and its underground system of more than 560 surveyed km of passageways are habitat to a varied flora and fauna, including a number of endangered species. The tour to this park can include cave tours, surface hiking, canoeing on the Green River, picnicking, horseback riding, cycling, camping and more.