The main water sources are surface waters. Only 24 of the 8,350 rivers are greater than  in length. All the rivers drain into the Caspian Sea in the east of the country. The largest lake is Sarysu (67 km2), and the longest river is Kur (1,515 km), which is transboundary with Armenia. Azerbaijan has several islands along the Caspian sea, mostly located in the Baku Archipelago.