Rio Abajo Forest Karst Cave Access Road

This brutal track drops into Rio Abajo’s karst landscape where limestone bedrock has collapsed into a moonscape of sinkholes, caves, and underground rivers. You’ll navigate between 60-foot-deep dolinas and around massive mogote hills while following old forestry roads that connect Cueva Ventana’s back entrance to the Dos Bocas reservoir spillway. The route requires threading narrow passages between house-sized boulders and fording underground streams that emerge from cave mouths before disappearing back into the earth.

Expert-level difficulty with mandatory rock crawling, steep limestone shelves, and zero margin for error on cliff-edge sections. Purpose-built 4WD with rock sliders, differential locks, and 35-inch tires minimum. Wet season (May-October) makes clay sections impassable and increases cave flood risk. Dry season only, with helmet and headlamp essential for cave exploration. You’ll access Puerto Rico’s most extensive underground river system and limestone formations that rival anything in the American Southwest. Water and fuel in Arecibo, notify someone of your plans.