Danube
The Danube was once a long-standing frontier of the Roman Empire, and today flows through 10 countries, more than any other river in the world. Originating in Germany, the Danube flows southeast for , passing through or bordering Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova and Ukraine before draining into the Black Sea. Its drainage basin extends into nine more countries. The Danube river basin is home to fish species such as pike, zander, huchen, Wels catfish, burbot and tench. It is also home to a large diversity of carp and sturgeon, as well as salmon and trout. A few species of euryhaline fish, such as European seabass, mullet, and eel, inhabit the Danube delta and the lower portion of the river.
Danube–Oder Canal
On December 8, 1939 Rudolf Hess inaugurated the then-named "Adolf Hitler Canal", today Gliwice Canal (Polish: "Kanał Gliwicki") from Kędzierzyn-Koźle at the Oder River to the city of Gliwice, that replaced the historic Kłodnica Canal finished in 1812. At the same time, Hess also performed the groundbreaking ceremony for the further "Donau-Oder-Kanal". The work on the Upper Silesian side already discontinued in 1940. Only a few kilometres of the planned 40-km long channel from Vienna to Angern at the Morava River were actually dug in the years up to 1943, mainly in the areas around the Lobau floodplain in the Donaustadt district of Vienna and the adjacent town of Groß-Enzersdorf. The branch-off at the Danube, just under 100 meters long, is still clearly recognizable today, connecting the "Ölhafen Lobau" of the OMV oil company. Two further sections are today used for swimming and fishing.