Herdecke is a town situated in the district of Ennepe-Ruhr-Kreis within the state of North Rhine-Westphalia, Germany. It is located south of Dortmund in the Ruhr Area region.
The town is notably positioned between two major Ruhr reservoirs, known as Hengsteysee and Harkortsee. Due to this specific geographical location, Herdecke is commonly referred to by the nickname Die Stadt zwischen den Ruhrseen.