isolated granite rock in the North Atlantic Ocean 220 miles (354 km) west of the Outer Hebrides, Scotland. Rockall is about 100 yards (91 metres) in circumference and stands some 70 feet (21 metres) above sea level. It was formally annexed by the United Kingdom in 1955 and incorporated as part of Scotland in 1972. The uninhabited islet has since assumed economic importance as a basis for oil and fishing rights in its territorial waters.