a lake on Mindanao Island, in the Philippines. Length, 28 km; maximum width, 14 km. The lake is situated at an altitude of 700 m, in a depression between volcanic massifs that is dammed up by a solidified lava flow. The banks of the lake are low lying and flat, and rice is cultivated in the marshy sections along the shore of the lake. The flow from Lake Lanao is to the north via the Agus River, which empties into Iligan Bay. The city of Marawi (Dansalan) is located at the source of the Agus River, which in its middle reaches has a hydroelectric power plant at the Maria Christina Falls.