Chiemsee is a freshwater lake in Bavaria, Germany, between Rosenheim, Germany, and Salzburg, Austria. It is often called the Bavarian Sea. The rivers Tiroler Achen and Prien flow into the lake from the South; the river Alz, out towards the North. The Chiemsee is divided into the bigger, north section, in the northeast, called Weitsee, and the Inselsee, in the southwest.