Sailing over the Danube with a paddle-boat. Sounds crazy huh? Flore and Manuel, both based in Berlin, are currently sailing down the Danube river on a paddle boat. A couple of days ago they started in Vienna and they are writing about their adventures at http://pepora.wordpress.com/
The Danube is Europe's second largest river with 2850 km, going from Black Forest in Germany to the Black Sea in Romania. See also this post by Hugo earlier this year about the idea to sail down the Danube with a self-made raft.