Lanao, also known as Rana, is the largest lake on the island of Mindanao, located in the southern province of Lanao. The total lake area – 340 sq. km, length – 33 km, width 20 km Maximum depth of the lake is 112 meters, average – 60, 3 meters. Lanao is considered one of the 15 ancient lakes in the world. Another feature is the location at an altitude of 700 m above sea level. Low-lying and flat shores Lanao widespread rice cultivation.

The lake falls 4 rivers, and flows only one – agus, which then flows into Iligan Bay. The river is notable for the beautiful Maria Cristina falls, which are sometimes called "waterfalls twins. Here built a hydroelectric power plant, which provides up to 70% of the electricity needs of the residents of Mindanao.

Lanao is the subject of many myths and legends of the local tribe maranao" - the very name of this tribe, means "people living on the shores of the lake." The myth describes the origin of the lake: a long time ago the angels led by Archangel Gabriel moved the inhabitants of one city in another place, that the world is not turned upside down from overpopulation. However, the resulting emptiness was soon filled with water, which was nearly flooded the rest of the world. To avert catastrophe, the angels called on the help of the four elements, so they made a hole, and water flowed – thus the lake Lanao and the agus river.

In 1992 the lake was declared a drainage reserve – this means that the vegetation on its banks, and water drainage are entitled to special protection to ensure water for hydropower, irrigation and agriculture. The area of the reserve is 153 thousand hectares On its territory you can find a great variety of species of flora and fauna, including several species of cyprinid fish that are endemic to the lake. In the early 1980s, researchers were concerned that these species are on the brink of extinction due to the negative impact of the HPP and the introduction of alien species. So, because of the appearance in the waters of white lake bullheads carp population has decreased from 18 species today there are only 5.