Mammoth Cave

Mammoth Cave is the world's longest cave

Mammoth Cave near Cave City, Kentucky, is the world's longest cave. More than 367 miles (591 km) of passages have been mapped. To get an idea of how long Mammoth Cave is, you should consider that the second longest cave in the world, Optimisticeskay Cave, in the Ukrainskaya region of the C.I.S. (former Soviet Union), is only 143 miles (230 km) long. Mammoth Cave is three times longer than its nearest competitor. Not only is the cave the longest in the world, but cave mappers believe the cave system will eventually prove to be 560 miles (900 km) long!

Mammoth Cave was formed in Mississippian-age limestone rock. The cave is 379 feet (118 m) deep, and contains at least 5 levels of passages. The levels were formed in response to changes in the Ohio River during the late Tertiary and Quaternary Periods. The lower levels of the cave are still active and subject to back flooding from the Green River. If you visit the park, tours are available on lighted paths and, for the more adventurous, a wild cave tour is available on a reservation basis. To find out more about the park, visit the Mammoth Cave Web site.

For all its magnitude, it should be remembered that Mammoth Cave is only one of many large caves in Kentucky. Kentucky is home to another 14 of the longest caves in the world. Prior to 1983, it was 3, but the 50 mile (80 km) long Roppel Cave System was connected to Mammoth Cave and removed from the list. The Fisher Ridge cave system currently ranks seventh on the world list, with a total length of 112 miles (180 km). Twelve other Kentucky caves are on the World's list of longest caves. A cave must have a minimum length of 15 km to be included on this list. To learn more about Kentucky caves, visit the list of caving organizations in Kentucky affiliated with the National Speoleological Society, or the National Speoleological Society website.


  • Dougherty, P.H., 1985, Caves and karst of Kentucky: Kentucky Geological Survey Special Publication 12, Series 11, 196 p. If you cannot find this publication in your library, it can be purchased from the Publication Sales Office of the Kentucky Geological Survey.
  • Currens, J. C.2002, Kentucky is karst country: What you should know about sinkholes and springs, Kentucky Geological Survey, Series 12, Information Circular 4, 29p.


Last Modified on 2019-08-22
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