The Mindanao River, also known as the Rio Grande de Mindanao, is the largest river system in the country. on the southern Philippine island of Mindanao. Approximately 320 km (200 miles) long, the river drains the majority of the central region of the island, and is an important transportation artery.
Its headwaters are in the mountains of northeastern Mindanao south of Butuan, where it is called the Pulangi river. Joining the Kabacan River, it becomes the Mindanao River. Flowing out of the mountains, it forms the center of a broad, fertile plain in the south-central portion of the island. Before its mouth in the Moro Gulf, it splits into two parallel sections, the Cotabato and Tamentaka, separated by a 180 m (600 foot) hill.