Understen
Encyclopedia
Understen is a Swedish island and lighthouse station located in South Kvarken
, east of Öregrund
at the northern tip of sea of Åland
in Sweden. The first day beacon on the island was built in the 18th century. The first lighthouse was built in 1848, and lit in November that year with a colza oil
lamp. In 1880 a kerosene
lamp was added but the lighthouse was considered too short (13 metres) and weak, and plans for the construction of a more powerful tower started. In 1916 the new much higher tower was completed and fitted with a powerful rotating Fresnel lens
in 1922. The old tower was not demolished and survives to this day, but its light equipment was removed. The keepers left their job in 1968, after the tower was automated in 1966. The island has been used as a station for the Swedish military due to its strategic location in the sea, and was staffed by military personnel in 1975-1996. On the island is also an observation tower built by the military. That tower is today fitted with remote controlled cameras observing the sea traffic in the area. The lighthouse remains in use and is still powered with electric cable and 1000 watt bulbs. It is owned by the Swedish Maritime Administration
, and remote controlled from their headquarters in Norrköping
. For many years, to visit the island permission had to be granted by the Swedish marine, but it is uncertain if this is valid nowadays (2010). The island can be observed on a distant view to the north from the ferries traveling between Grisslehamn
and Ekerö on Åland.
SMA has confirmed that many Russian and Swedish mines dating from the first and second world war may still lie on the sea buttom east of the light station, making anchoring or diving dangerous in the area.
South Kvarken
South kvarken is the narrowest stretch of sea between Finnish Åland and Sweden, forming a strait connecting the Sea of Åland and the Bothnian Sea of approximately 30 km across....
, east of Öregrund
Öregrund
Öregrund is a locality situated in Östhammar Municipality, Uppsala County, Sweden with 1,555 inhabitants in 2010. It is located by the coast of the Baltic Sea. Öregrund is, despite its small population, for historical reasons often still referred to as a city.- History :The town was granted a royal...
at the northern tip of sea of Åland
Sea of Åland
The Sea of Åland is the waters located in the southern Gulf of Bothnia, between the Åland islands and the Swedish mainland. The sea connects Kvarken and the Bothnian Sea with the Baltic Sea proper. The seas are often choppy here. The narrowest part is named Södra Kvarken or South Kvarken....
in Sweden. The first day beacon on the island was built in the 18th century. The first lighthouse was built in 1848, and lit in November that year with a colza oil
Colza oil
Colza oil is a nondrying oil obtained from the seeds of Brassica rapa, var. oleifera, a variety of the plant that produces turnips. Colza is extensively cultivated in France, Belgium, the United States, the Netherlands and Germany and Poland. In France, especially, the extraction of the oil is an...
lamp. In 1880 a kerosene
Kerosene
Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...
lamp was added but the lighthouse was considered too short (13 metres) and weak, and plans for the construction of a more powerful tower started. In 1916 the new much higher tower was completed and fitted with a powerful rotating Fresnel lens
Fresnel lens
A Fresnel lens is a type of lens originally developed by French physicist Augustin-Jean Fresnel for lighthouses.The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design...
in 1922. The old tower was not demolished and survives to this day, but its light equipment was removed. The keepers left their job in 1968, after the tower was automated in 1966. The island has been used as a station for the Swedish military due to its strategic location in the sea, and was staffed by military personnel in 1975-1996. On the island is also an observation tower built by the military. That tower is today fitted with remote controlled cameras observing the sea traffic in the area. The lighthouse remains in use and is still powered with electric cable and 1000 watt bulbs. It is owned by the Swedish Maritime Administration
Swedish Maritime Administration
The Swedish Maritime Administration is the Swedish government agency which provides services to the transport sector by keeping the sea lanes open and safe...
, and remote controlled from their headquarters in Norrköping
Norrköping
Norrköping is a city in the province of Östergötland in eastern Sweden and the seat of Norrköping Municipality, Östergötland County. The city has a population of 87,247 inhabitants in 2010, out of a municipal total of 130,050, making it Sweden's tenth largest city and eighth largest...
. For many years, to visit the island permission had to be granted by the Swedish marine, but it is uncertain if this is valid nowadays (2010). The island can be observed on a distant view to the north from the ferries traveling between Grisslehamn
Grisslehamn
Grisslehamn is a locality situated in Norrtälje Municipality, Stockholm County, Sweden with 277 inhabitants in 2010.It is located on the coast by the Sea of Åland; the Eckerö Linjen ferries between Åland and Sweden operate between Grisslehamn and Eckerö on Åland.The name Grisslehamn was first...
and Ekerö on Åland.
SMA has confirmed that many Russian and Swedish mines dating from the first and second world war may still lie on the sea buttom east of the light station, making anchoring or diving dangerous in the area.