Vitsø Nor is a large, protected fjord area covering c. 150 hectares that was navigable in the 17th century. During the 18th and 19th centuries, several large fjord areas of Ærø were reclaimed, including Vitsø Nor and Gråsten Nor, where parts of the reclaimed areas are still uncultivated and are used for grazing or haying.
The area is highly valuable in terms of biology due to its abundance of wild flora and fauna, and, in terms of cultural history, it is treasured as the setting of Søbygaard/Søby Volde, a medieval castle on high ground, one of the largest and prettiest castle mounds in Denmark.