And for those river areas away from the towns and cities, the following image is not an uncommon situation (this photo was taken outside Warsaw on June 2013).
You can see why river navigation requires a little more thought than the weekend leisure boat crowd typically employ!
Image source: Post #154, posted by forum user Zbig , date posted 1st Jun 2013
http://www.rcgroups.com/forums/showt...811191&page=11