This is a list of tributaries of the Danube by order of entrance. The Danube is Europe's second-longest river. It starts in the Black Forest in Germany as two smaller rivers—the Brigach and the Breg—which join at Donaueschingen, and it is from here that it is known as the Danube, flowing generally eastwards for a distance of some 2850 km, passing through several Central and Eastern European capitals, before emptying into the Black Sea via the Danube Delta in Romania. The Danube flows through—or forms a part of the borders of—ten countries: Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Romania, Moldova, and Ukraine; in addition, the drainage basin includes parts of nine more countries: Poland, Switzerland, Italy, Czech Republic, Slovenia, Bosnia and Herzegovina, Montenegro, North Macedonia and Albania.