Drinking water Along its course, the Danube is a source of drinking water for about 20 million people. In
Baden-Württemberg,
Germany, almost 30 percent (as of 2004) of the water for the area between
Stuttgart,
Bad Mergentheim,
Aalen and
Alb-Donau (district) comes from purified water of the Danube. Other cities such as
Ulm and
Passau also use some water from the Danube. In
Austria and
Hungary, most water is drawn from ground and spring sources, and only in rare cases is water from the Danube used. Most states also find it too difficult to clean the water because of extensive pollution; only parts of Romania where the water is cleaner still obtain drinking water from the Danube on a regular basis.
Navigation and transport on the Danube in Lower Austria, 1982 In the 19th century, the Danube was an important waterway but was, as
The Times of London put it, "annually swept by ice that will lift a large ship out of the water or cut her in two as if she were a carrot." Today, as
"Corridor VII" of the
European Union, the Danube is an important transport route. Since the opening of the
Rhine–Main–Danube Canal, the river connects the
Port of Rotterdam and the industrial centers of Western Europe with the
Black Sea and, also, through the
Danube – Black Sea Canal, with the
Port of Constanța. The waterway is designed for large-scale inland vessels () but it can carry much larger vessels on most of its course. The Danube has been partly canalized in Germany (5 locks) and Austria (10 locks). Proposals to build a number of new locks to improve navigation have not progressed, due in part to environmental concerns. Downstream from the
Freudenau locks in Vienna, canalization of the Danube was limited to the
Gabčíkovo dam and locks near Bratislava and the two double
Iron Gate locks in the border stretch of the Danube between Serbia and Romania. These locks have larger dimensions. Downstream of the Iron Gate, the river is free flowing all the way to the Black Sea, a distance of more than . The Danube connects with the Rhine–Main–Danube Canal at
Kelheim, with the
Donaukanal in Vienna, and with the Danube–Black Sea Canal at
Cernavodă. Apart from a couple of secondary navigable branches, the only major navigable rivers linked to the Danube are the
Drava,
Sava and
Tisa. In Serbia, a canal network also connects to the river; the network, known as the
Danube–Tisa–Danube Canals, links sections downstream. In the Austrian and German sections of the Danube, a type of flat-bottomed boat called a
Zille was developed for use along the river. Zillen are still used today for fishing, ferrying, and other transport of goods and people in this area.
Fishing The importance of fishing on the Danube, which was critical in the
Middle Ages, has declined dramatically. Some fishermen are still active at certain points on the river, and the
Danube Delta still has an important industry. However, some of the river's resources have been managed in an environmentally unsustainable manner in the past, leading to damage by pollution, alterations to the channel, and major infrastructure development, including large hydropower dams. The
sturgeon stocks associated with the Danube river basin have, over the centuries, formed the basis of a large and significant commercial fishery, renowned throughout the world. The construction of the dams, besides overfishing and river pollution, has a significant role in sturgeon population decline because it creates a barrier for fish migratory species that usually spawn in the upper parts of the river. The spawning areas of migratory fishes species has been dramatically reduced by the construction of hydropower and navigation systems at Iron Gates I (1974) and Iron Gates II (1984). The initial design of these dams has not included any fish passage facility. The possibility of building a human-made
fish pass enabling migration for fish species including the sturgeon, is currently under review by projects such as We Pass. The Upper Danube
ecoregion alone has about 60 fish species and the Lower Danube–
Dniester ecoregion has about twice as many. Among these are an exceptionally high diversity of sturgeon, a total of six species (
beluga,
Russian sturgeon,
bastard sturgeon,
sterlet,
starry sturgeon and
European sea sturgeon), but these are all threatened and have largely–or entirely in the case of the European sea sturgeon–disappeared from the river.
Tourism above the Danube near
Spitz, Austria Important tourist and natural spots along the Danube include the
Wachau Valley, the
Nationalpark Donau-Auen in Austria,
Gemenc in Hungary, the
Naturpark Obere Donau in Germany,
Kopački rit in Croatia,
Iron Gate in Serbia and Romania, the
Danube Delta in Romania, and the
Srebarna Nature Reserve in Bulgaria. Also, leisure and travel cruises on the river are of significance. Besides the often frequented route between Vienna and Budapest, some ships even go from
Passau in Germany to the
Danube Delta and back. During the peak season, more than 70 cruise liners are in use on the river, while the traffic-free upper parts can only be discovered with canoes or boats. The Danube region is not only culturally and historically of importance, but also important for the regional tourism industry due to its fascinating landmarks and sights. With its well established infrastructure regarding cycling, hiking, and travel possibilities, the region along the Danube attracts every year an international clientele. In Austria alone, there are more than 14 million overnight stays and about 6.5 million arrivals per year. The Danube Banks in
Budapest are a part of Unesco World Heritage sites, they can be viewed from a number of sightseeing cruises offered in the city. The Danube Bend is also a popular tourist destination.
Danube Bike Trail in the
Bohemian Massif The
Danube Bike Trail (also called Danube Cycle Path or the
Donauradweg) is a bicycle trail along the river. Especially the parts through Germany and Austria are very popular, which makes it one of the 10 most popular bike trails in Germany. The Danube Bike Trail starts at the origin of the Danube and ends where the river flows into the Black Sea. It is divided into four sections: •
Donaueschingen–
Passau () •
Passau–
Vienna () •
Vienna–
Budapest () •
Budapest–
Black Sea ()
Sultans Trail The
Sultans Trail is a hiking trail that runs along the river between
Vienna and
Smederevo in Serbia. From there the Sultans Trail leaves the Danube, terminating in
Istanbul. Sections along the river are as follows. •
Vienna–
Budapest () •
Budapest–
Smederevo ()
Donausteig In 2010, the
Donausteig, a hiking trail from Passau to
Grein, was opened. It is long and it is divided into 23 stages. The route passes through five Bavarian and 40 Austrian communities. A landscape and viewpoints, which are along the river, are the highlights of the
Donausteig.
The Route of Emperors and Kings The Route of Emperors and Kings is an international touristic route leading from
Regensburg to Budapest, calling in Passau, Linz and Vienna. The international consortium
ARGE Die Donau-Straße der Kaiser und Könige, comprising ten tourism organisations, shipping companies, and cities, strives for the conservation and touristic development of the Danube region. ==Important national parks==