Lake Constace or Lake of Constance (German: "Bodensee") is a large Lake on the river Rhine. It is on the border between Germany and Switzerland and Austria. It is the third largest lake in Central Europe after Lake Balaton and Lake Geneva. It is made of two smaller lakes (called "Obersee" and "Untersee" (Upper and lower lake) respectively). These are joined by a small part of river in Constance.