Lake Constance
There are three big islands in the lake. The islands Lindau and Mainau are in the Obersee. Reichenau is in the Untersee. The Obersee is about  long, from Bregenz to Bodman-Ludwigshafen. It is about  wide at its widest point between Romanshorn and Friedrichshafen. The deepest point is  deep, between Fischbach and Uttwil (just off Constance).