The Kali Gandaki Gorge or Andha Galchi is the gorge of the Kali Gandaki (or Gandaki River) in the Himalayas in Nepal. Gorge depth is difficult to define due to disagreement over rim height, but by some measures the Kali Gandaki is the deepest gorge in the world.
The upper part of the gorge is also called Thak Khola after the local Thakali people who became prosperous from trans-Himalayan trade. Geologically, it is a downfaulted graben.
The gorge separates the major peaks of Dhaulagiri (8,167 m/26,795 ft) on the west and Annapurna (8,091 m/26,545 ft) on the east. If one measures the depth of a canyon by the difference between the river height and the heights of the highest peaks on either side, the gorge is the world's deepest. The portion of the river directly between Dhaulagiri and Annapurna I (7 km downstream from Tukuche) is at an elevation of 2520 metres, 5571 metres lower than Annapurna I. The river is older than the Himalayas. As tectonic activity forced the mountains higher, the river cut down through the uplift. This region is known for shaligram fossils, revered as one of five non-living forms of Lord Vishnu.
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 7 km south of Tukuche in the area of Lete. The gorge then broadens past Dana and Tatopani toward Beni.
Jomsom (Nepali: जोमसोम), also known as Dzongsam or New Fort, is a town located at an altitude of 2800m in Mustang District, Nepal. It extends over both the banks of the Kali Gandaki River. Along the banks of Kali Gandaki river there are rocks holy to the Hindus. The soaring peaks of Dhaulagiri and Nilgiri form a backdrop. As the district headquarters, it is primarily an administrative and commercial center with government officials and merchants rubbing shoulders with the local residents of the region, known as Thakalis. A company of the Nepalese Army is stationed here. Nearby is Jomsom Airport from where there are regular flights.
A trail passes through the Lower Mustang region of Nepal, ending at the village of Kagbeni, a Tibetan influenced village filled with prayer wheels, chortens and a Buddhist monastery. The trail follows the Kali Gandaki River which forms the deepest ravine in the world; on one side lies the Annapurna mountain range and on the other side is Dhaulagiri. Between the two ranges, there are views of 8 of the 20 highest mountains in the world. The Kali Gandaki is a quarter of a mile wide river bed; during the winter the river will be dry, but during the summer and monsoon it fills with rain water and melting snow. The scenery of the trail ranges from forests of bright red rhododendrons (Nepali: लालीगुँरास) to rocky cliffs and desert. The culture along the track is a rich mixture of Hindu and Tibetan Buddhism. The trail's highest point is Muktinath at 3800 m, a holy site of temples sacred to both Buddhists and Hindus for centuries.