Cagayan River 3.65

The Cagayan River, also known as the Rio Grande de Cagayan, is the longest river in the Philippines and the largest river by discharge volume of water (followed by Rio Grande de Mindanao). It has a total length of approximately and a drainage basin covering. It is located in the Cagayan Valley region in northeastern part of Luzon Island and traverses the provinces of Nueva Vizcaya, Quirino, Isabela and Cagayan.TopographyThe river's headwaters are at the Caraballo Mountains of the Central Luzon at an elevation of approximately. The river flows north for some to its mouth at the Babuyan Channel near the town of Aparri, Cagayan. The river drops rapidly to above sea level some from the river mouth. Its principal tributaries are the Pinacanauan, Chico, Siffu, Mallig, Magat and Ilagan Rivers.