Some of Scandinavia and Northern Europe's most iconic cities are included on a Baltic Sea cruise, giving you time to soak in the sights and culture of Copenhagen, Stockholm, Oslo, and Helsinki, as well as Tallinn, Estonia, and St. Petersburg, Russia. Copenhagen and Stockholm are the most common departure points for this route (trips are usually 10 to 14 days), while some lines launch from Dover or Southampton, England. If you choose a longer cruise, additional ports could include Riga, Latvia; Gdansk, Poland; and Warnemunde, Germany, the closest cruise port to Berlin.