Colossal Cave is a large cave system in southeastern Arizona. It contains about 3.5 miles of mapped passageways.
If tight squeezes, narrow ledges and crevasses are your thing, Colossal Cave offers a special tour just for you. To go on the tour, hard hats, lights, and full-fingered (work) gloves are required. Knee and elbow pads are recommended.
For many, this video may be as close as you’ll want to get to being in inside the Earth.