The Rhein river rises in the Swiss Alps and flows north,forming the western borders of Liechtenstein and Austria,then fills the Bodensee (Lake of Constance) between Switzerland and Germany.
Kilometer measurements start at the German city of Konstanz, as the river leaves the Bodensee, and continue to the North Sea, at KM1031.
The Rhein is canalized along the French border, from Basel to Strasbourg, then at Iffezheim (Germany) it continues north as an open river, with no locks, to the Dutch border. The final kilometer post in Germany is KM865.5, where the Rhein becomes the Waal in the Netherlands.
Everyone knows of the castles on the Rhine, and the Rhine Gorge (above) is the most scenic section, but there is a lot more to this river, the busiest in Europe. The northern section passes through a flat plain, the industrial heart of Germany, and offers interesting stops at Köln (Cologne) and Koblenz. At Koblenz the ridges rise on both sides of the river, with great views of castles and vineyards. The Rhine intersects with the Main river at Mainz, near Frankfurt, and connects via the Rhein-Main-Donau Kanal with the Danube for a route all the way to the Black Sea.
Sankt Goar, in the Rhein gorge
The Rhine Gorge, between Mainz and Koblenz, is very scenic: a narrow river valley between steep rocky cliffs, including the Lorelei rock.