The Peak Cavern, also known as the Devil's Arse, is one of the four show caves in Castleton, Derbyshire, England.

Unlike the other caves in the area, it is entirely natural, and the cave system is the largest in the Peak District. The Peak Cavern Entrance is the largest in Britain and was formerly home to a small village devoted to rope making, while the depths of the cave were known as a haven for bandits.

The system contains Titan Shaft, at 145m the deepest pitch in Britain.