Iskanderkul is a mountain lake of glacial origin in Tajikistan's Sughd Province. It lies at an altitude of on the northern slopes of the Gissar Range in the Fann Mountains. Triangular in shape, it has a surface area of and is up to deep. Formed by a landslide that blocks the Saratogh river, the outflow of the lake is called the Iskander Darya, which joins the Yaghnob River to form the Fan Darya, a major left tributary of the Zeravshan River.