An isolated granite stack in the Atlantic Ocean, Rockall (the 'Sea-rock of Roaring', Gael: Sgeir Rocail) lies 186 miles (300 km) west of St Kilda. Rising to c.19m (63 feet), it is the furthest outlier of the British Isles and gives its name to a Shipping Forecast Area that is bounded to the north by Bailey, northeast by Hebrides, east by Malin and south by Shannon.
The British Navy landed in 1810 and it was surveyed by Captain A.T.E. Vidal of the Royal Navy in 1831. However, it was not until 18th September 1955 that the rock was claimed for Britain, principally to prevent the Soviet Union spying on missile tests. A helicopter from the survey ship HMS Vidal landed a Royal Marine, Sergeant Brian Peel, who planted the Union Jack, attached a plaque and collected biological specimens.
A navigation light installed in 1972. In the same year, the Isle of Rockall Act was enacted to strengthen Britain's title and protect against competing claims from Iceland and Ireland. This Act also assigned the rock to Scotland, becoming part of the county of Inverness-shire. It was subsequently transferred to the Western Isles Council.