Jewel Cave

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.

Cave

Caves and caverns are natural voids under the surface of the Earth and have also been observed in other rocky worlds. Caves often form by the weathering of rock and can extend deep underground. Exogene caves are smaller openings that extend a relatively short distance underground. Caves which extend farther underground than the opening is wide are called endogene caves.

jewel

Noun

1. A precious or semi-precious stone; gem, gemstone.
2. A valuable object used for personal ornamentation, especially one made of precious metals and stones; a piece of jewellery.

Verb

1. To bejewel; to decorate or bedeck with jewels or gems.

cave

Noun

1. A large, naturally-occurring cavity formed underground or in the face of a cliff or a hillside.
2. A hole, depression, or gap in earth or rock, whether natural or man-made.

Verb

1. To surrender.
2. To collapse.