Devils Hole is a geologic formation located in a detached unit of Death Valley National Park and surrounded by the Ash Meadows National Wildlife Refuge, in Nye County, Nevada, in the Southwestern United States. Devils Hole is habitat for the only naturally occurring population of the endangered Devils Hole pupfish (Cyprinodon diabolis). The 40 acres (16 ha) unit is part of the Ash Meadows complex, an area of desert uplands and spring-fed oases that was designated as a National Wildlife Refuge in 1984.