The Danube - A truly European river. With its 2888 kilometres from its source in the Black Forest to its mouth in the Black Sea, the Danube connects ten countries with very different cultures. And this makes it not only the second longest European river after the Volga, but also the most international river in the world. It was and is one of the most important trade routes in Europe and is the lifeline for many people. On its way, it flows through spectacular landscapes, from the karst mountains of the Swabian Alb, through floodplains and marshlands with unique flora and fauna, to the imposing canyons of the Iron Gate and finally the extensive river delta at the mouth into the Black Sea. Not only is the Danube's size extraordinary, it also has a will of its own and is the only major river in Europe to flow from west to east. This film series presents nature and people along the Danube river and gives insights into different lifestyles shaped by the river. In Part 1, the film follows the river from its source to Linz in Upper Austria. Even at its origin, the Danube poses riddles; to this day, at least two different sources circulate in literature. Sensitive ecosystem The young Danube runs through the karst mountains of the Swabian Alb. In the sensitive ecosystem, head forester Markus Ellinger controls the recreational athletes, because strict rules prevail on, in and on the water. In Ulm, modernity and history meet. A fashion photo shoot takes place on a historic "Ulmer Schachtel", the type of boat many Swabians used to emigrate to the East in the 18th century. Europe's river with the most fish species Past Regensburg and Passau, the river crosses the border into Austria. In Engelhartszell, fish biologist Gerald Zauner wants to bring people closer to the aquatic world of the Danube. The Danube is the river with the most fish species in Europe. The Hausen, the largest of the sturgeon family, is also native to the Danube and can be admired here. Elisabeth Strauß is on night duty at the Ottensheim-Wilhering lock. How does the lock-keeper fare as a woman in a male domain? In the forward-looking Upper Austrian city of Linz, street artist SIUZ embellishes a barren industrial wall in the Danube Harbour Gallery with a tern. The graffiti in the harbour gallery is exposed to wind and weather and is not static, just like the Danube, which flows ever eastwards.