Jewel Cave National Monument contains Jewel Cave, currently the third longest cave in the world, with 209. 32 miles (336. 87 kilometers) of mapped passageways. It is located approximately 13 miles (21 km) west of the town of Custer in Black Hills of South Dakota. It became a national monument in 1908.
This article uses material from the Wikipedia article “Jewel Cave National Monument“, which is released under the Creative Commons Attribution-Share-Alike License 3.0.