The Blyde River Canyon is a significant natural feature of South Africa, located in Mpumalanga, and forming the northern part of the Drakensberg escarpment. It is 25 kilometres (16 mi) in length and is, on average, around 750 metres (2,461 ft) deep. The Blyderivierpoort Dam, when full, is at an altitude of 665 metres (2,182 ft). The Canyon consists mostly of red sandstone. The highest point of the canyon, Mariepskop, is 1,944 metres (6,378 ft) above sea level, whilst its lowest point where the river leaves the canyon is slightly less than 561 metres (1,841 ft) above sea level.