What lies beneath can be cold, damp and compelling. Learn about dry and wet caves, the creatures that live in them and the characteristics that create these natural settings. Here are five places to explore underground: 1. Kartchner Caverns, Benson, Arizona In 1974, two University of Arizona students and amateur cavers spotted a narrow crack in the bottom of a sinkhole. They followed the unusually moist air and discovered more than 2 miles of unspoiled cave passages. The caverns, carved from limestone, were not opened to the public until 1999 and are part of the Arizona State Park system. Visi…