The Flensburg Firth stretches about 40 km from the city to the open Baltic, with the German and Danish coastlines running parallel on either side. The water is calm and relatively shallow, making it ideal for sailing, kayaking, and windsurfing. Several beaches on both the German and Danish shores are reachable by boat or by short drives from the city.
The harbour promenade in central Flensburg gives the best views of the Firth and is the starting point for boat trips. In summer, ferries run to points along the Danish coast. The light here on clear days — a flat Baltic light that photographers and painters have long favoured — is one of the genuine pleasures of the area.