Explore Jewel Cave National Monument, South Dakota
Thirteen miles west of Custer City via US 16, the surface of Jewel Cave National Monument covers 1,274 acres. Believed to be the third-longest cave in the world—with more than 170 miles of mapped and surveyed passages—Jewel Cave is still being explored. Its subterranean chambers and limestone galleries are noted for the nailhead calcite crystals lining the walls. Learn More...