The area of sea below mean high water springs enclosed by a line beginning on the mainland of Orkney at 58°53−44'North latitude 2°53−50'West longitude; then west, north and south along the shoreline to a point on the mainland of Orkney at 58°57−06'North latitude 3°00−00'West longitude; then south to a point on South Ronaldsay at 58°49−52'North latitude 3°00−00'West longitude; then east along the shore line to a point at 58°50−25'North latitude 2°54−19'West longitude, to Churchill Barrier No. 4; then west, east and north along the shoreline to the Churchill Barriers on the north shore of the island of Burray, then north along the west side of the Churchill Barriers to the point of beginning.