Jewel Cave National Monument contains Jewel Cave, currently the fifth longest cave in the world and second longest cave in the United States, with of mapped passageways as of July 2025. It is located approximately west of the town of Custer in the Black Hills of South Dakota.

Jewel Cave became a national monument in 1908, becoming the first national monument established for the protection and preservation of a cave. In addition to its length, the cave is significant for being one of the best known examples of a breathing cave, in which changes in outside air pressure cause air to flow into and out of the cave. Jewel Cave is named for the calcite crystals that cover many of its walls.

Mission

The monument's mission is stated in its foundation document:

After enlarging the cave entrance with dynamite, the Michaud brothers found a cavern lined with calcite crystals, which led them to name it "Jewel Cave". The brothers tried to capitalize on the discovery, widening the opening, building walkways inside, and opening it to tourists. Although their venture was unsuccessful and they had to sell their mining claim back to the government, news of the discovery eventually reached Washington. President Theodore Roosevelt proclaimed Jewel Cave a national monument on February 7, 1908. The area around the natural entrance to the cave was further developed by the Civilian Conservation Corps in the 1930s. The National Park Service assumed management of the monument from the United States Forest Service in 1933 and began offering tours in 1939. This puts estimates for the total length somewhere between roughly and . The cave volume is estimated by measuring the amount of air that the cave "exhales" when the outside air pressure drops and "inhales" when the outside air pressure rises. This was first explained by Herb Conn in 1966. The temperature inside the cave is year-round.

Although much of Jewel Cave is dry, over a dozen underground lakes have been discovered where the cave meets the Madison Aquifer, about below the surface. The first of these, Hourglass Lake, was discovered in 2015.

Flora and fauna

Jewel Cave is one of the largest bat hibernacula in the United States. Thousands of bats of ten different species live in and around the cave throughout the year, including several species which hibernate in the cave during the winter. Bat numbers have decreased significantly since 2018, when the fungus that causes white-nose syndrome was first discovered in Jewel Cave.

Other animals living on the surface include bighorn sheep, mule deer, white-tailed deer, mountain lions, coyotes, packrats, garter snakes, prairie rattlesnakes, great horned owls, blue jays, red-headed woodpeckers, western tanagers, cliff swallows, and occasional American black bears and elk.

Access and infrastructure

thumb|left|Jewel Cave National Monument's main visitor center complex

Jewel Cave is open year-round. Surface amenities include a visitor center, park theater, natural history exhibits, park store, hiking trails, and picnic areas. To enter the cave, visitors must take a ranger-guided tour.

thumb|Visitors and guide inside Jewel Cave

The National Park Service offers four tours seasonally: the Scenic Tour, a half-mile loop through a paved and lighted central portion of the cave accessed by elevator; the Discovery Tour, a short accessible tour to a single, large room of the cave; the Historic Lantern Tour, a lantern-lit tour through the earliest-discovered part of the cave; and the Wild Caving Tour, through an undeveloped part of the cave near the scenic loop. The Wild Caving Tour requires visitors to squeeze through a passageway less than tall. The historic trail, cave entrance, and ranger station were listed in the National Register of Historic Places in April 1995.

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File:Jewel Cave National Monument 03.jpg|The historic visitor center, built by the Civilian Conservation Corps in the 1930s

File:Jewel Cave National Monument 10.jpg|Trail to Jewel Cave's historic entrance

File:Jewel Cave National Monument 19.jpg|Interior view of Jewel Cave's historic entrance

File:The Crushing Deep is currently one of the deepest known parts of Jewel Cave. (ea7f45eb-cc56-fa1c-afff-131ef8d9b0fd).JPG|The Crushing Deep, one of the deepest known parts of Jewel Cave

File:Jewel Cave 1.jpg|Much of Jewel Cave is covered with calcite spar crystals, but they are rarely as clear as this cluster.

File:Jewel Cave 2.jpg|Calcite crystals cover much of the walls in some sections of the cave. Typically they are a dull brown color as in this room.

File:Jewel Cave is a dry cave, but areas with "wet" formations such as these stalagmites and stalactites do exist. (ea3f6ae9-be6d-220e-3d57-658de86879dd).JPG|Jewel Cave is mainly a dry cave, but areas with "wet" formations such as these stalagmites and stalactites do exist.

File:Bacon Strip Jewel Cave koopas.JPG|Cave bacon, a type of drapery seen on the Scenic Tour

File:Jewel Cave 3.jpg|Aragonite frostwork is another speleothem found throughout the cave, typically in small crusts on the walls.

File:Gypsum flowers are typically only found in dry areas of Jewel Cave. (eb8214a0-ba30-b9ad-62f7-34d22e66831e).JPG|Gypsum flowers are typically only found in dry areas of Jewel Cave.

File:A caver looks at a cave formation called a logomite. (ea1af457-04fe-082f-ada5-4d0b6fd02a07).JPG|A caver looks at a cave formation called a logomite.

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See also

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  • Lehman Caves
  • Mammoth Cave National Park
  • Oregon Caves National Monument and Preserve
  • Russell Cave National Monument
  • Speleology
  • Timpanogos Cave National Monument
  • Wind Cave National Park
  • List of caves
  • List of longest caves
  • List of longest caves in the United States
  • List of national monuments of the United States

References

Further reading

  • (describes the exploration of Jewel Cave from its discovery to the mid-1980s)
  • Official website at the National Park Service
  • Official park film: Jewel Cave: Discovery in the Darkness