Cagayan River or Rio Grande de Cagayan, with a total length of 353 kilometers, is the longest and widest river in the Philippines. It bisects the Cagayan Valley from north to south. Also considered as the mightiest watercourse, Cagayan River sources its water from smaller rivers and streams in the mountain ranges of Sierra Madre, Caraballo, Cordillera, and Balete Pass.

 

This river meets the South China Sea in an impressive expanse known as Aparri Delta. The other notable rivers in Luzon are Chico, Abra, Pampanga, and Bicol. In the south, the principal rivers are Mindanao (known in its upper course as the Pulangi) and Agusan.

 

Meanwhile, the underground river of St. Paul's Natural Park in Palawan is considered as one of the world's longest subterranean rivers. The world's longest rivers are the Nile River in Egypt and Amazon River in South America. Also worth mentioning are the Yangtze River in China, Mekong River in Vietnam, and Euphrates River in Iraq.

 

 

Rio Grande de Mindanao, is the second largest river system in the Philippines, after the Cagayan River of Luzon. It is also the largest river on the southern Philippine island of Mindanao having a drainage area of 23,169 square kilometers, 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 373 km (231.8 miles)[1]. It is an important transportation artery on the island, used mainly in transporting agricultural products and, formerly, timber.

Its headwaters are in the mountains of Bukidnon, south of Gingoog City in Misamis Oriental, 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.