The Strait of Dover or Dover Strait, is the strait at the narrowest part of the English Channel, marking the boundary between the Channel and the North Sea, and separating Great Britain from continental Europe. The shortest distance across the strait, at approximately 20 miles, is from the South Foreland, northeast of Dover in the English county of Kent, to Cap Gris Nez, a cape near to Calais in the French département of Pas-de-Calais. Between these points lies the most popular route for cross-channel swimmers. The entire strait is within the territorial waters of France and the United Kingdom, but a right of transit passage under the United Nations Convention on the Law of the Sea allows vessels of other nations to move freely through the strait.

The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busiest shipping area in the world.