| an arm of the Atlantic between Great Britain and the European mainland. ab. 201,000 sq. mi. (520,600 sq. km); greatest depth, 1998 ft. (610 m). |
| North Sea An arm of the Atlantic Ocean between Great Britain and northwest Europe. It is connected with the English Channel by the Strait of Dover. Major reserves of oil and natural gas were discovered beneath its waters in the late 1960s. |
Arm of the Atlantic Ocean northwest of central Europe.
Note: Oil was discovered under the sea floor in 1970.