Strait of Dover

Dover, Strait of, narrow passage separating southeastern England from northern France, connecting the English Channel with the North Sea. It is about 19 mi (30 km) across at its narrowest point. The chief ports are Dover and Folkestone in England, Calais and Boulogne in France. Of great strategic importance, the strait was the scene of the first repulse by the English of the Spanish Armada (1588), the Dover (antisubmarine) Patrol of World War I, and the evacuation from Dunkirk (1940). The strait is frequently crossed by long-distance swimmers.