Neffs Cave

Neffs Cave (or Neffs Canyon Cave) is a cave in Neffs Canyon on the north side of Mount Olympus, directly east of Millcreek, Utah in the United States. It is one of the deepest caves in the United States but is seldom entered despite its depth and its proximity to Salt Lake City. The United States Forest Service has closed the cave to the public for many years due to safety hazards. In 1977, Neffs Canyon Cave was designated as a National Natural Landmark by the National Park Service.

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