The Guil is a torrential river that, like the Po, has its source in the region of Mount Viso, the highest peak in the Cottian Alps. It travels about 31 miles (50 kilometers) through the Queyras valley before flowing into the Durance at the foot of Mont-Dauphin in the Hautes-Alpes department. The Guil constitutes the common element of the two territories of Queyras and Guillestrois to which it gave its name.