The English Channel

The English Channel is the body of water that separates southern England from northern France and links the southern part of the North Sea to the Atlantic Ocean. It is the busiest shipping area in the world.

 

It is about 560 km (350 mi) long and varies in width from 240 km (150 mi) at its widest to 33.3 km (20.7 mi) in the Strait of Dover. It is the smallest of the shallow seas around the continental shelf of Europe, covering an area of some 75,000 km2 (29,000 sq mi).
Captain Matthew Webb made the first observed and unassisted swim across the Strait of Dover, swimming from England to France on 24–25 August 1875 in 21 hours 45 minutes.