What is the deepest valley in the world?
Kali Gandaki Gorge
The Kali Gandaki river source coincides with the Tibetan border and Ganges-Brahmaputra watershed divide. The river then flows south through the ancient kingdom of Mustang. It flows through a sheer-sided, deep canyon immediately south of the Mustang capital of Lo Manthang, then widens as it approaches Kagbeni where high Himalayan ranges begin to close in.  The river continues southward past Jomsom, Marpha, and Tukuche to the deepest part of the gorge about 7km south of Tukuche in the area of Lete. The gorge then broadens past Dana and Tatopani toward Beni.