Stockholm with its natural harbors and access to the Baltic Sea has naturally seen many visitors coming here by waterways. The biggest, as far as I know, must be MS Navigator of the Seas, ranked among the largest passenger cruise ships in the world. She's really HUGE, I remember in 2007, when she was about to arrive here, the Port of Stockholm made a special arrangement just to make sure she's fine to dock here.
Another memorable visitor was Götheborg, a replica of the historic vessel bearing the same name from the eighteenth century, coming to Stockholm in 2008. One year before Götheborg just returned to Sweden after its much celebrated 20-month voyage to China. You could see her in the background of this picture, with the sails visible.