Lake Lanao is a large lake in the Philippines, located in Lanao del Sur province in the country’s southern island of Mindanao. With a surface area of 340 km2 (130 sq mi), it is the largest lake in Mindanao, and the second largest lake in the Philippines and counted as one of the 15 ancient lakes in the world.
Lake Lanao used to be home to 18 endemic fish species, Cyprinids, which is a large family of freshwater fish that include carps, minnows, and barbs, with 3 endemic species left. All 18 species are thought to have evolved from one species, the spotted barb.
The lake was formed by the tectonic-volcanic damming of a basin between two mountain ranges and the collapse of a large volcano. It has a maximum depth of 122 m (400 ft), and a mean depth of 60.3 m (198 ft). The basin is shallowest towards the north and gets progressively deeper towards the south.
The lake is fed by four rivers. Its only outlet is the Agus River, which flows northwest into Iligan Bay via two channels, one over the Maria Cristina Falls and the other over the Linamon Falls. A hydroelectric plant installed on the Lanao Lake and Agus River system generates 70% of the electricity used by the people of Mindanao.
The lake is a home of myths and legends of the Meranaw tribe. The name Meranaw was derived from the name of the lake and it means “the people living around the lake”.