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. The Isar flows through Bad Tölz, Munich and Landshut before reaching the Danube near Deggendorf. The length is . It is the fourth largest river in Bavaria (after Danube, Inn and Main). The Isar is the second most important tributary of the Danube in Germany, after Inn.