The Hengsen reservoir, located north of the Ruhr and south of Holzwickede, is known for its idyllic location and the cormorant island. This small island in the middle of the lake is home to a breeding colony of cormorants. Over the years, the cormorants' concentrated excrement has largely destroyed the island's vegetation. The Hengsen reservoir is also used to produce drinking water and borders the Bahnwald nature reserve directly to the north. Despite being used for drinking water, there is a walking path at the western end of the lake that provides a direct view of the lake and the island. The quiet location also benefits the endangered wildlife.
In addition to the cormorants, the Hengsen reservoir also offers bird watchers the opportunity to observe other bird species such as greylag geese, Canada geese, mute swans, Egyptian geese, mallards, little grebes, great crested grebes and tufted ducks. The area is best explored by bicycle, with parking available approximately 1 km away. The approximately 10 km long circular route leads through forest, grassland, agricultural areas, along the lake and through urban areas. The conditions are flat and the route is easy to walk, making it an ideal destination for bird watchers and nature lovers.