The Himalayas in the south of Tibet have an average of 6,000 meters, the highest range on the earth. Their main peak, 8,848-metre Mount Qomolangma on the Sino-Nepalese border, is the summit of the globe. In the north are the Kunlun range and its branch, the Tanggula Mountains; in the middle the Gangdise range; and in the east the Hengduan range with numerous canyons and imposing mountains. North of the Gangdise range and south of the Kunlun range is the vast Northern Tibet Plateau. The Southern Tibet Valleys between the Gangdise and the Himalayas, crossed by the Yarlungzangbo River from west to east, are the principal farming and pastoral area of Tibet.
Tibet's major rivers include the Yarlungzangbo, Nujiang, Lancang and Jinsha. The Tibet Plateau, one of the regions in China with the greatest number of lakes, has numerous salt lakes, the largest being Nam Co. In all, lakes cover a total area of some 30,000 square kilometers on the plateau. Tibet ranks second in the country in hydroelectric power potentials.