The Pinacanauan River is a tributary of the Cagayan River that flows past the base of the Callao Cave complex in Peñablanca. Its lower stretch, alongside the caves, is the most popular — clear water, limestone outcrops, and forested banks create a striking river landscape. Kayaks and small bangka boats can be hired from operators near the cave entrance for paddling along the quieter sections. The river is clean enough for swimming in the dry season, when water levels drop and visibility is good. Combined with a visit to the caves, a couple of hours on the river makes for a full day out from Tuguegarao.