Route: River Danube Sea to Source

This route follows Europe's second largest river, the Danube, from the Black Sea coast at Sulina in Romania, to the source in Donaueschingen, Germany near the Black Forest.

It passes through eight countries (Romania, Bulgaria, Serbia, Croatia, Hungary, Slovakia, Austria and Germany), four capital cities (Belgrade, Budapest, Vienna and Bratislava). A real mix of terrain, it follows roads, trails, off-road river paths, paved dyke roads, over bridges and border crossings, through tiny remote villages and towns and major cities.

The route runs along much of the established EuroVelo cycling routes (mainly EuroVelo 6) that run close to the Danube. As a runner it's possible to occasionally depart from these routes, where it's possible to run closer to the river. 

The full route, with stage by stage descriptions, can be found here:

https://www.komoot.com/collection/1626685/-danube-sea-to-source-actual-route-running-the-blue