Iskanderkul is a mountain lake of glacial origin in Tajikistan's Sughd Province. It lies at an altitude of 2195 m on the northern slopes of the Gissar Range in the Fann Mountains. Triangular in shape, it has a surface area of 3.4 km2 and is up to 72 m deep. Claimed to be one of the most beautiful mountain lakes in the former Soviet Union, it is a popular tourist destination.
The lake takes its name from Alexander the Great: Iskander is the Persian pronunciation of Alexander, and kul is lake in Tajik, which is of Turkic origin.
The outflow of the lake is the Iskander Darya, which joins the Yaghnob River to form the Fan Darya, a major left tributary of the Zeravshan River.