To the south, Nanga Parbat has what is often referred to as the highest mountain face in the world: the Rupal Face rises 4,600 m (15,090 ft) above its base.[10] To the north, the complex, somewhat more gently sloped Rakhiot Flank rises 7,000 m (23,000 ft) from the Indus River valley to the summit in just 25 km (16 mi), one of the ten greatest elevation gains in such a short distance on Earth.[citation needed]