The Peak Speedwell System is located in the village of Castleton, made up of Peak Cavern, Speedwell Mine, James Hall Over Engine Mine and Titan Shaft. The system contains about 18km of cave passage, one of the deepest underground cave dives in the UK, down to a depth of 74 metres; the highest underground pitch in the UK which is 145 metres high, it has six known entrances but only four are usable.