Abulog
The Abulog or Abulug is the 9th largest river system in the Philippines in terms of watershed size. It has an estimated drainage area of and a length of 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.
The upper reaches of the Abulug River, especially upstream from Kabugao, is commonly known as the Apayao River.
