In the location's words:

Kirchhorster See is an idyllic quarry pond in Isernhagen near Hanover - around 4.8 hectares in size and up to 7.5 m deep. It was created in the 1950s during the expansion of the A7 motorway and was officially opened as a bathing lake in 1969. On the eastern shore you will find a sandy beach, a playground lawn and a jetty with a bathing platform, ideal for families, those seeking peace and quiet and ambitious swimmers. Free admission, but "swim at your own risk" and there is no water supervision. Please note: In the dry summer months, aquatic plants such as algae can proliferate. In 2023, an indefinite bathing ban was even imposed as soon as the creepers became too dangerous.