The Kahayan river, or Great Dyak, is the largest river in Central Kalimantan, a province of Indonesia in Kalimantan - the Indonesian part of the island of Borneo. The provincial capital Palangkaraya lies on the river. The main inhabitants are Dyaks, who practice slash-and-burn rice cultivation and pan for gold on the upper reaches. The lower Kayahan flows through a rich and unusual environment of peat swamp forests, which has been severely degraded by an unsuccessful program to convert a large part of the area into rice paddies, compounded by legal and illegal forestry.