The Schifffahrtsmuseum (Museum of Shipping) and Rum Museum occupy a building in the harbour district and cover the two pillars of Flensburg's commercial history: the Baltic Sea trade and the Caribbean rum business. The shipping collection includes model ships, navigational instruments, and documentation of the city's role as a regional trading port over six centuries.
The rum section is the more distinctive of the two, documenting the extraordinary story of how a mid-sized German city became the centre of the German rum trade through an accident of Danish colonial history. The collection includes antique bottling equipment, trading records, and a range of historical Flensburg rum labels. Combined, the two collections make this the most informative museum in the city.