Which major tributaries join the Danube River?

The Danube River features a dense network of approximately 300 tributaries. These waterways are categorized by their location along the river's course:1

• Upper Course: The Inn River is the largest upstream tributary. Other significant tributaries in this section include the Iller, Lech, Isar, Traun, Enns, and Morava rivers.1
• Middle Course: This section receives the waters of the Danube's most affluent tributaries, which significantly alter the river's regime: the Drava, the Tisza, and the Sava.1
• Lower Course: Tributaries in this region are comparatively smaller and include the Olt, the Siret, and the Prut.1

More than half of the entire Danube basin is drained by its right-bank tributaries, which originate in the Alps and other mountainous regions, contributing up to two-thirds of the total river runoff.1