This is a list of tributaries of the Danube by order of entrance.
The Danube is Europe's second-longest river, with a length of , and a drainage basin of . It starts in the Black Forest in Germany as two smaller rivers—the Brigach and the Breg—which join at Donaueschingen, after which it is known as the Danube.
From there it flows generally eastwards through—or forming a part of the borders of—Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Romania, Moldova, and Ukraine, before emptying into the Black Sea via the Danube Delta in Romania. Its drainage basin includes parts of nine more countries: Poland, Switzerland, Italy, Czech Republic, Slovenia, Bosnia and Herzegovina, Montenegro, North Macedonia and Albania. <br> <br>