Ziernsee is a lake in the Mecklenburg Lake District, in Germany. Whilst most of the lake is in the district of Mecklenburgische Seenplatte (municipality Priepert) in the state of Mecklenburg-Vorpommern, a portion of its southern shore is in the state of Brandenburg. The lake has an elevation of 54.6 metres (179 ft) and a surface area of 1.1 square kilometres (0.42 sq mi).