Neffs Canyon Cave, Salt Lake City, Utah

Neffs Canyon Cave sits right at the edge of Salt Lake City in Millcreek Canyon — the longest urban cave in the United States with over a mile of mapped passage. The cave requires a permit from Salt Lake County. The hike to the entrance follows the Neffs Canyon Trail and climbs steeply through pine and oak before reaching the boulder-covered entrance. Inside, the cave demands serious belly crawls and tight squeezes through the breakdown. The ceiling is low in sections and there is some interesting scalloping on the limestone walls indicating ancient swift water flow. A cold cave with no formations near the entrance, becoming more decorated toward the back sections.