Finnish boats and coal merchant Rönström
A wealthy coal merchant built the large house on Finnhamn as a summerhouse in 1915. The islands were bought by Stockholm City in 1943 and became the first “recreation reserve” that the city bought, with the intention of saving it from private exploitation. Finnhamn was handed over to the Archipelago Foundation in 1998, Kålgårdsön was handed over in 2002.
The reserve is bordered by the Finnhamn reserve. A trench that could be navigated by canoe 50 years ago marks the border between the two islands. There are no antiquities on Kålgårdsön, but mounds are scattered throughout the island as memories of the previously cultivated land. The reserve also includes the islets Klippingen, Knokan and Bockholmen by Stora Rävsön.