Amper basin

Ammersee (; English: Lake Ammer) is a Zungenbecken lake in Upper Bavaria, Germany, southwest of Munich between the towns of Herrsching and Dießen am Ammersee. With a surface area of approximately , it is the sixth largest lake in Germany. The lake is at an elevation of , and has a maximum depth of . Like other Bavarian lakes, Ammersee developed as a result of the ice age glaciers melting. Ammersee is fed by the River Ammer, which flows as the Amper out of the lake. Like neighbouring Lake Starnberg - deeper, bigger in surface area, similar in shape - it is a popular location for watersports.

The Amper (), called the Ammer () upstream of the Ammersee, through which it runs, is the largest tributary of the Isar in southern Bavaria, Germany. It flows generally north-eastward, reaching the Isar in Moosburg, about from its source in the Ammergau Alps, with a flow of 45 m3/s. Including its tributary, Linder, it is long. Major tributaries are the Glonn, which rises near Augsburg; the Würm, which is the outflow of Lake Starnberg; and the Maisach.