Osmussaar, Odensholm in Swedish, is located in the Baltic Sea, 7 kilometres off the northwest coast. The island is 5 kilometres long and about 1.5 kilometres wide. The Estonian Swedes themselves called the island Holmen while the people living on Osmussaar often used the name Backan.
The island has not undergone extensive archaeological exploration, but archaeologists have found signs of a Viking stopover at the chapel. It makes sense, since the island is located along the trade route from the Varangians to the Greeks. Written sources first mention Osmussaar in the 13th century, but Swedes living on the island are first mentioned in 1430.
There was only one village and it was located at the very centre of the island. The number of farms varied between 5 and 10 over the centuries. There were seven families living on the island from the 18th century until 1940: Brus, Stavas, Niggors, Erkers, Marks, Nybondas and Greis.
The surrounding fields and meadows were shared by the whole village, but divided into stringed fields – each farm had its own strip. Farming was mainly done by women. Locals cultivated barley and potatoes, but the main income came from fish sold on the mainland. The islanders also hunted long-tailed ducks and seals. Pilotage services for ships bound for Haapsalu, Tallinn or Riga also meant extra income. For this reason, each farm had a raised ladder overlooking the sea. The island had a lifeboat, and the islanders were exempt from military service. Looting of grounded and/or wrecked ships also provided some income.
Osmussaar belonged to under Uuemõisa manor. As the island was remote and it was not possible to go to the manor for mandatory work, the islanders limited themselves to paying rent. The rent remained unchanged from the 17th century – 5 barrels of salt and the same amount of fresh fish per year.
In 1902, Osmussaar was sold to von Schutz by Hunnius, the lord of Uuemõisa manor. In 1907, it was resold. At the beginning of the 20th century, there was a demand for the people of Osmussaar to buy out their land, but they refused to do so, insisting on the privileges granted by Queen Christina of Sweden, which specified a compulsory annuity of fish.
About a hundred or so people lived on Osmusaar. There were 130 residents before World War II. As a result of the 1939 Soviet–Estonian Mutual Assistance Treaty, the residents of the island were forced to leave the island in June 1940. Two weddings were held on the island the day before their departure on 12 June. The residents of Osmussaar were resettled on Vormsi, but because of the poor farmland there, they tried to migrate to Riguldi, which was also a more familiar place for the islanders. The Russians built military bases on Osmussaar. During the German occupation, the islanders were allowed to return to their home island. They found that their village had been destroyed. In 1943-1944, the Swedes of Osmussaare who had not been mobilised into the Soviet army relocated to Sweden.
During the Soviet era, there was a small border guard unit on the island and lighthouse keepers lived with their families near the lighthouse. In 1993 the soldiers left the island and it remained uninhabited for ten years.
As the land on the island did not belong to the residents there before World War II, they had no right to reclaim it. Today, Osmussaar belongs to the state and the island has been a protected area since 1994.
Permanent residents returned to the island at the start of the 2000s, with one family living there year round.