The Mummelsee has a circumference of approximately 800 m (2,625 ft) and is surrounded by steep and forested mountain slopes on its northern, western and eastern sides. The western lakeside rises towards the mountain Katzenkopf (1,123 m (3,684 ft) above sea level) and the northern lakeshore rises towards Hornisgrinde. With 1,163 m (3,816 ft) above sea level, Hornisgrinde is the highest mountain in the Northern Black Forest. Solely the southern lake banks are (nearly) flat. This also being the place where the alpine hotel Mummelsee and the close-by St. Michaels chapel are located.