Neffs Cave

Neffs Cave, or Neffs Canyon Cave, is a deep limestone cave in Neffs Canyon east of Millcreek, Utah, on the north side of Mount Olympus. Discovered in 1949 by brothers John and Jamie Lyon, it soon gained a reputation for danger after early explorers were trapped and later parties encountered major drops. Exploration by the National Park Service and, especially, the Salt Lake Grotto of the National Speleological Society established its great depth, later revised to 1,163 feet, ranking it among the deepest caves found in the United States. Though sparsely decorated, it is important for its geology, exploration history, and National Natural Landmark status.

Holladay, Utah · United States