The Kali Gandaki Gorge or Andha Galchi is the gorge of the Kali Gandaki (or Gandaki River) in the Himalayas in Nepal. It 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, the gorge is within a structural graben.

The gorge separates the major peaks of Dhaulagiri (8,167 m or 26,795 ft) on the west and Annapurna (8,091 m or 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 Kali Gandaki gorge has been used as a trade route between India and Tibet for centuries. Today, it is part of a popular trekking route from Pokhara to Muktinath, part of the Annapurna Circuit. The gorge is within the Annapurna Conservation Area.

More Info: en.wikipedia.org