Mammoth Cave is one of Utah’s largest lava tubes, formed less than 2,000 years ago on the Markagunt Plateau in southern Utah as cooling lava and water shaped its interior. In Dixie National Forest, it contains more than 2,200 feet of passage, with an overall length of about a quarter mile. The cave stays cool year-round because of its elevation and interior moisture. It has four chambers, including a larger western chamber, and a narrow opening at the end of the main tunnel that can also serve as an exit. Seasonal closures protect hibernating bats, and winter snow can block Mammoth Creek Road.