Kartchner Caverns State Park is a state park of Arizona, United States, featuring a show cave with 2.4 miles of passages. The park is located 9 miles south of the town of Benson and west of the north-flowing San Pedro River. Long hidden from view, the caverns were discovered in 1974 by local cavers, assisted by a state biologist who helped in its preservation. The park encompasses most of a down-dropped block of Palaeozoic rocks on the east flank of the Whetstone Mountains.