The Rio Grande de Mindanao, also known as the Mindanao River, is the second largest river system in the Philippines, after the Cagayan River of Luzon. It is the largest river on the southern island of Mindanao with a drainage area of draining majority of the central and eastern portion of the island. It is also the second longest river in the country with a length of approximately . It is an important transportation artery on the island, used mainly in transporting agricultural products and, formerly, timber.