Jewel Cave National Monument

11149 US Highway 16, Bldg. B12, Custer, SD 57730

The third-longest cave in the world features a variety of cave tours below the surface and a 1,279-acre park with nature trails above ground. With a name derived from the crystals that line its walls, Jewel Cave is even more significant as one of the longest caves in the world, with more than 208 miles of mapped and surveyed passages. Located near Custer in the southern Black Hills, this national monument also features three self-guided above-ground trails: the Roof Trail, the Canyons Trail and the Hell Canyon Trail. Plus, there is a visitor center with an information desk, park store, exhibits, a theater, information about the Junior Ranger program and more.