The Iller is a river in Bavaria and Baden-Württemberg in Germany. It is a right tributary of the Danube. The Iller is 146 km long.
It is situated in the Allgäu area of the Alps, near the Austrian border, at the meeting point of the rivers Breitach, Stillach, and Trettach, close to Oberstdorf. It then continues north, past the towns of Kempten, Immenstadt, and Sonthofen. Between Lautrach near Memmingen and Ulm it forms the border between Bavaria and Baden-Württemberg for about 50 kilometres (31 mi). The river flows into the Danube in Ulm.
