In a valley between the Jenner, Hagen, and Watzmann Mountains, Königssee is Bavaria’s deepest lake at about 630 feet deep. The purity of the water is partly because gas motors have been banned at the lake since 1909. You are allowed to go swimming. If you plan to visit Berchtesgaden make sure you have some time. Königssee itself will take all day, cause the secret waits behind the Königssee. Lake Obersee.