Stralsund's Old Town is an island, almost entirely surrounded by water — the Strelasund to the north and east, three lakes to the south and west. The Hanseatic architecture is exceptional: the Town Hall (Rathaus) with its Gothic tracery facade and the brick churches of St. Nikolai, St. Marien, and St. Jakobi rank among the finest in northern Germany.
The Ozeaneum on the harbour is the headline modern attraction — a striking aquarium building with tanks housing North Sea and Baltic Sea ecosystems including enormous shark tanks. The German Museum of Military History — Naval Section occupies a former historic shipyard and is also worth a visit.
The Altstadt (Old Town) is compact enough to explore thoroughly on foot in a day. From the harbour, ferries and excursion boats head to the islands of Rügen and Hiddensee.