Cagayan Valley (Lambak ng Cagayan in Filipino) is a region of the Philippines, also designated as Region II or Region 02. It is composed of five provinces, namely: Batanes, Cagayan, Isabela, Nueva Vizcaya, and Quirino. Its regional center is Tuguegarao City.
Most of the region lies in a large valley in northeastern Luzon, between the Cordilleras and the Sierra Madre mountain ranges. Cagayan River, the country's longest river runs through its center and flows out to Luzon Strait in the north, in the town of Aparri, Cagayan. The Babuyan and Batanes island groups that lie in the Luzon Strait also belong to the region.