North Sea, arm of the Atlantic Ocean, c.222,000 sq mi (574,980 sq km), c.600 mi (1,000 km) long and c.400 mi (640 km) wide, NW of Central Europe. It washes the shores of Great Britain, Norway, Denmark, Germany, the Netherlands, Belgium, and the northern tip of France. In the south the Strait of Dover connects it with the English Channel. The North Sea is deepest (c.2,165 ft/660 m) along the coast of Norway and contains several shallows, the largest of which is the Dogger Bank, midway between England and Denmark. The herring fisheries of the North Sea are economically important, but the cod and haddock stocks have declined significantly. In 1970 oil was discovered under the seafloor. During the 1970s the oil resources were garnered by Great Britain, West Germany, Denmark, Norway, and the Netherlands.