Catacombs Cave

Catacombs Cave is a 6,903 foot (2, 104 m) cave in Lava Beds National Monument in California. It is considered one of the most challenging caves accessible in the park. This very long cave is easily entered, but gradually increases in difficulty. It is possible to walk upright for approximately 800 feet (240 m) to the stairway, after which the ceiling rarely exceeds 3 feet (0.91 m). A few places exist where the ceiling height is less than 12 inches (300 mm).

Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).