Mammoth Cave National Park, Kentucky by Ken Lund

Mammoth Cave National Park is a U.S. National Park in central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world. The official name of the system is the Mammoth-Flint Ridge Cave System for the ridge under which the cave has formed. The park was established as a national park on July 1, 1941. It became a World Heritage Site on October 27, 1981, and an international Biosphere Reserve on September 26, 1990. The park's 52,830 acres (21,380 ha) are located primarily in Edmonson County, Kentucky, with small areas extending eastward into Hart County and Barren County. It is centered on the Green River, with a tributary, the Nolin River, feeding into the Green just inside the park. With 400 miles (640 km) of surveyed passageways Mammoth Cave is by far the world's longest known cave system, being over twice as long as the second-longest cave system, Mexico's Sac Actun underwater cave. The National Park Service offers several cave tours to visitors. Some notable features of the cave, such as Grand Avenue, Frozen Niagara, and Fat Man's Misery, can be seen on lighted tours ranging from one to six hours in length. Two tours, lit only by visitor-carried paraffin lamps, are popular alternatives to the electric-lit routes. Several &quot;wild&quot; tours venture away from the developed parts of the cave into muddy crawls and dusty tunnels. The lectures delivered by the National Park Service cave guides are varied by tour, so that in taking several tours the visitor learns about different facets of the cave's formation, or of the cave's human history and prehistory. <a href="http://en.wikipedia.org/wiki/Mammoth_Cave_National_Park" rel="nofollow">en.wikipedia.org/wiki/Mammoth_Cave_National_Park</a> <a href="http://en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_Attribution-ShareAlike_3.0_Unported_License" rel="nofollow">en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_...</a>