Čertova skála, Nature reserve on the left bank of the Berounka, Hracholusky nad Berounkou, Czech Republic.

Čertova skála is a nature reserve on the left bank of the Berounka in the Křivoklátsko Protected Landscape Area. Its several vertical rock walls, the most massive natural spilite wall in the Bohemian Massif, expose pillow lavas formed by underwater eruptions about 600 million years ago.

The area gained protected status in 1949 to preserve its rock formations and ecological systems for future generations. This legal protection has remained in place and continues to guide conservation efforts.

The name comes from a legend of a fisherman from the Kouřimecká rybárna, a place that appears in stories by Ota Pavel. He promised his daughter to the devil if a bridge over the Berounka stood before the cock crowed; the devil had built the abutment and two piers when the fisherman lit a lantern in the henhouse and the cock crowed early, leaving the bridge unfinished.

Marked trails wind through the reserve and connect various observation points where wildlife can be viewed. Sturdy footwear is recommended due to the hilly and rocky terrain.

The rock face is the thickest natural wall of spilite in the entire Bohemian Massif, formed from pillow lavas that erupted on the sea floor about 600 million years ago. The rounded, cushion-like shapes visible in the outcrops are more resistant to weathering than the surrounding greywacke and shale.