Helen's Reef

Helen's Reef is a line of skerries in the North Atlantic about two kilometers northeast of Rockall, lying within United Kingdom claimed waters under the Island of Rockall Act 1972. Rather than a coral reef, it is built of igneous rock, specifically microgabbro with olivine dolerite, dated to the Late Cretaceous period some 81 million years ago and linked to the volcanic processes that opened the early North Atlantic. The skerries are covered at high tide or in rough seas and are usually visible only as breaking waves, and take their name from the brigantine Helen of Dundee, which was wrecked there in 1824. The reef's worst recorded disaster came in 1904, when the steamship SS Norge sank there with the loss of 635 lives.