Rockall

British islet in the Atlantic, 24 m/80 ft across and 22 m/65 ft high, part of the Hatton-Rockall bank, and 370 km/230 mi west of North Uist in the Hebrides. The bank is part of a fragment of Greenland that broke away 60 million years ago. It is in a potentially rich oil/gas area. The islet is uninhabited. A party of British marines landed in 1955 formally to annex Rockall, but Denmark, Iceland, and Ireland challenge Britain's claims for mineral, oil, and fishing rights. The Rockall Trough between Rockall and Ireland, 250 km/155 mi wide and up to 3,000 m/10,000 ft deep, forms an ideal marine laboratory.

A 1995 study by the Natural History Museum of 17 seabed sites (including the Great Barrier Reef and the San Diego Trough) revealed that the Rockall Trough had more species than any other site, and greater biodiversity than a coral reef. In 4 cubic metres/5 cubic yards of sediment there were 325 species of worm.