Danube
The Danube flows through many cities, including four national capitals (shown below in bold), more than any other river in the world. Ordered from the source to the mouth they are:
The Danube is navigable by ocean ships from the Black Sea to Brăila in Romania and by river ships to Kelheim, Bavaria, Germany; smaller craft can navigate further upstream to Ulm, Württemberg, Germany. About 60 of its tributaries are also navigable.
Floridsdorf
The Danube forms the southwestern border district. A part of the New Danube and a section of the Danube Island are in Floridsdorf, while the water area immediately beyond the Danube island is in the Döbling district area. The Vienna Danube bridges to Floridsdorfer area (ranked in the direction of flow of the Danube) are: the Bridge Jedleseer, the North Bridge, the North Bridge, the Bridge Floridsdorfer, the North Bridge, the U6-Danube Bridge and Brigittenauer Bridge. In Floridsdorf is also the northern part of the Old Danube. In 1992, the Marchfeld channel was put into operation, which crosses the district area.