Lake Zurich is a lake in Switzerland, extending southeast of the city of Zurich. Depending on the context, Lake Zurich or Zürichsee can be used to describe the lake as a whole, or just that part of the lake downstream of the Hurden peninsula and Seedamm causeway. In the latter case, the upstream part of the lake is called Obersee, whilst the lower part is sometimes also referred to as the Lower Lake, respectively.