The Isar is a river in Tyrol, Austria and Bavaria, Germany. Its source is in the Karwendel range of the Alps in Tyrol; it enters Germany near Mittenwald, and flows through Bad Tölz, Munich, and Landshut before reaching the Danube near Deggendorf. At 295 km (183 mi) in length, it is the fourth largest river in Bavaria, after the Danube, Inn, and Main.