Most Coober Pedy locals live underground; spending a night in a dugout is the closest a visitor gets to the experience. Several "underground motels" tunnel into the same kind of bedrock as the residential dugouts, with rooms that hold a steady 22–24°C year-round regardless of the 45°C outside. No windows; surprisingly quiet.
The two longest-established underground motels are the Desert Cave Hotel on Hutchison Street and the Underground Motel on Catacomb Road; there are several smaller B&Bs. Book ahead in winter — that is the busy season — and ask for an underground room specifically; some properties have both.