Callao Cave is one of the most well-known natural attractions in Peñablanca, Cagayan, located within the Peñablanca Protected Landscape and Seascape along the foothills of the Sierra Madre mountain range. It is about 24 kilometers from Tuguegarao City and forms part of a broader karst system in the area, where more than 300 caves have been documented, making the municipality an important site for both geological and ecological studies.