The Hanseatic port of Stralsund sits on the mainland at the gateway to Rügen, just across the bridge. It is a UNESCO-listed brick-Gothic town with three towering medieval churches — St. Nikolai, St. Marien, St. Jakobi — and a beautifully restored Altstadt of stepped gables and cobbled streets.
The Ozeaneum, a striking white modern aquarium on the harbour, is one of the best aquariums in Europe, with a tank of Baltic species, a North Sea hall, and a giant whale-skeleton exhibit. The German Maritime Museum (Deutsches Meeresmuseum) is housed across multiple sites in town.
Stralsund is 20 minutes by train from Bergen auf Rügen and makes an easy day out from anywhere on the island.