Szczecin in North-Western Poland has a deep commitment to sail training. Discover the Underground City Trails: a network of bunkers from WWII with their unique atmosphere. If you're more of an outdorsy type, take a canoe along the Odra river or explore Bukowe Hills which hide the ruins of old bridges and are home to numerous boars and deer. Visit one of many museums or the Castle of Pomeranian Dukes or the beautiful rose gardens.
Rostock is a large city on the Warnow River, and home to one of the oldest universities in the world. One of the most picturesque places in Rostock is the Neuer Markt (New Market Square), with the Town Hall - that was originally built in the 13th century in Brick Gothic style. The square also preserved six original, carefully restored gable houses from the 15th and 16th centuries. There are a lot more historical and cultural sights to see in this city. So go ahead, and explore!