Heiliger See

Heiliger See is a lake within the city limits of Potsdam, Brandenburg, Germany, located northeast of the city center and bordering the historic park known as the New Garden. Together with the lakes Sacrower See and Groß Glienicker See to the north it forms a chain of lakes resulting from a glacial tunnel valley. The lake is 1.33 km long and 300 metres wide on average.

Because of its picturesque location amidst the historic parks and palaces of Potsdam, with the Marmorpalais on its west shore and Cecilienhof near the north shore, the lake is a popular goal for excursions and has an attractive residential area on its eastern shore.

Source: Wikipedia