The Danube
The Danube is the second longest river in Europe (after the Volga) and the river that flows through more countries than any other river in the world. It crosses or borders ten countries on its 2,860 km journey from the Black Forest of Germany to the Black Sea. Four European capitals sit on its banks: Vienna, Bratislava, Budapest and Belgrade.
- Length2,860 kmSecond longest river in Europe
- Countries10More than any other river in the world
- SourceBlack Forest, GermanyTwo small streams meet to start it
- MouthBlack SeaThrough a huge delta in Romania and Ukraine
- Capitals4Vienna, Bratislava, Budapest, Belgrade
- Famous for"The Blue Danube"A waltz by Johann Strauss, 1866
How long is the Danube compared to other rivers?
The Danube is the second longest river in Europe after the Volga in Russia. It is the world's most international river, flowing through more countries than any other.
What is the Danube?
The Danube is a major river in central and southeastern Europe, flowing eastward from Germany to the Black Sea. The ten countries it touches are Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova and Ukraine. For most of its course it forms part of borders between countries, and for thousands of years it has been a vital trade route, military frontier and cultural artery.
A border through history
For approx. 400 years, the Danube formed the northern frontier of the Roman Empire. The Romans built a chain of forts along its southern bank to keep out the Germanic tribes on the other side. Many modern European cities (Vienna, Budapest, Belgrade) began as Roman frontier forts on the Danube.
In later centuries the river was a frontier between the Ottoman Empire and the Habsburg Empire, and during the Cold War between the Communist East and the democratic West (the Iron Curtain ran along the Danube in Austria and Hungary). For most of European history, controlling the Danube meant controlling the centre of Europe.
The Iron Gates
One of the most spectacular sections of the Danube is the Iron Gates, a series of deep gorges where the river cuts through the Carpathian Mountains on the border between Serbia and Romania. Until the 1960s the rapids here made navigation dangerous. Two enormous hydroelectric dams (Iron Gates I and II) were built in the 1960s and 1970s to control the river, generate electricity and let ships pass safely.
The Danube Delta
The Danube ends in a huge wetland on the Romanian and Ukrainian coast called the Danube Delta. This is one of the most important wetlands in Europe and a UNESCO World Heritage Site. It is home to over 300 species of bird, including white pelicans, pygmy cormorants, egrets and herons, plus thousands of migrating birds that stop on their way between Africa and northern Europe.
Deeper dive: Danubian civilisations, the Iron Gate dams and modern challenges
The Danube basin was the home of some of the earliest civilisations of Europe. The Vinča culture (around 5500 to 4500 BC) developed sophisticated pottery and what may have been one of the world's earliest writing systems. The Hallstatt culture of the Iron Age (around 1200 to 500 BC) controlled trade along the upper Danube and produced fine metalwork. The Romans incorporated most of the river into their empire as the provinces of Raetia, Noricum, Pannonia, Moesia and Dacia from the 1st to the 4th centuries AD. After the fall of Rome, the Danube became the central artery of a series of empires (Bulgarian, Byzantine, Ottoman, Habsburg) that shaped Europe for over a thousand years.
The construction of the Iron Gate dams in the 1960s and 1970s was a major engineering and ecological project. Iron Gate I (commissioned 1972) and Iron Gate II (1985) are joint Romanian-Yugoslav (now Romanian-Serbian) hydroelectric projects with a combined capacity of approx. 2.5 gigawatts. The dams flooded around 130 km of valley and required relocating around 23,000 people, including the entire island town of Ada Kaleh, a Turkish-speaking community that had survived in the gorge for centuries. The dams have also blocked fish migration, contributing to the near-extinction of several sturgeon species that historically swam up the Danube to spawn from the Black Sea.
The modern Danube faces serious environmental pressures. The river has lost most of its natural floodplains to agriculture and flood-control levees. Industrial pollution, especially from former Communist-era factories, has improved since the 1990s but is still a concern. The Beluga sturgeon, which once swam up the Danube as far as Vienna and produced the highest-quality caviar, is now critically endangered. International cooperation through the International Commission for the Protection of the Danube River, signed by all the countries it touches, is gradually improving water quality and restoring some natural wetlands. The Danube Delta in Romania is one of the great success stories: it has been protected as a Biosphere Reserve since 1990 and its bird populations are growing again.
The longest river in Europe is the Volga in Russia. The four capitals along the Danube include Vienna and Budapest.