The Danube River is a river located in central and southeast Europe, flowing 1,725 miles from southern Germany to the Black Sea. It is the second-longest river in Europe.
The Danube passes through or touches the borders of 10 different countries, and its drainage basin, which is roughly twice the size of California, extends into nine other countries. This makes the river the most multinational in the world. The river also flows through many cities and the capitals of four countries.
The Danube river provides a water source for around 20 million people who live along its banks. While some countries pull water directly from the river for drinking, other countries get their drinking water elsewhere because pollution in the river makes cleaning it for drinking difficult. It is also important to agriculture, transportation and industry in the area. In the Middle Ages, fishing was vital on the Danube. However, the importance of fishing has declined dramatically in most areas of the river.
The Danube is home to a large number of fish species and to a particularly diverse population of sturgeon. In total, six species of sturgeon live in the river. The populations of these fish are all threatened, however, and one species, the European sea sturgeon, has disappeared completely.