The Abulog River or Abulug River is the 9th largest river system in the Philippines in terms of watershed size.[1][2] It has an estimated drainage area of 3,372 square kilometres (1,302 sq mi) and a length of 196 kilometres (122 mi) from its source in the mountains of Apayao in the Cordillera Administrative Region. More than 90% of the drainage area of the river is located in Apayao province while the remaining, including the mouth of the river, is in Cagayan province.