Tags: Lighthouse, Tower.
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.
