Germany - Travel by boat
Germany has several harbors in the North, like Hamburg, Cuxhaven, Bremerhaven, Luebeck, all of which can be reached by boat.
Under http://www.kueste.de/kanal/passagierschiffliste.htm you
can find ports of entrée and destinations (site in German only).
Passenger cruising on the Rhine, Mosel and other rivers in Germany is very common and many liners offer a great range of daily trips.
One of the sites with more information: http://www.k-d.com/englisch/index.html
In the South of Germany you can go on cruise ships on the Ammersee, Starnberger See, Woerther See, Bodensee, Inninger See and many more.
Look up http://www.fuenfseen.de/freizeit/anzeige.php for more information (in German only).
If you want to cruise the Donau, please have a look at: http://www.kreuzfahrt-angebote-online.de/Donau.1380.0.html (in German only). You could start in Passau, the city of the 3 rivers and go all the way up to Hungary for example. It is a real dream trip.