Jewel Cave National Monument
| Jewel Cave National Monument | |
|---|---|
The Inner Sanctum, one of the longest and largest passageways along the Scenic Tour | |
Interactive map of Jewel Cave National Monument | |
| Location | Custer County, South Dakota, U.S. |
| Nearest city | Custer, South Dakota |
| Coordinates | 43°43′46″N 103°49′46″W / 43.72944°N 103.82944°W |
| Area | 1,273 acres (5.15 km2) |
| Created | February 7, 1908 |
| Visitors | 145,332 (in 2024) |
| Governing body | National Park Service |
| Website | Jewel Cave National Monument |
Jewel Cave National Monument contains Jewel Cave, currently the fifth longest cave in the world and second longest cave in the United States, with 220.33 miles (354.59 km) of mapped passageways as of July 2025. It is located approximately 13 miles (21 km) 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.