Maibritt, the Girl from the Islands(1964)

Original title: Maibritt, das Mädchen von den Inseln

A German businessmen is sent to Stockholm by his boss to secure an important contract, in the face of foreign competition. He discovers that the intended client has gone sailing round the Swedish islands and follows him. He becomes mixed up with a mysterious young woman named Maibritt, who eventually turns out to be the daughter of his intended client.