Which is the largest swimming course in the world

Which is the largest swimming course in the world

دنیا کا سب سے بڑا سوئمنگ کورس ....... ہے۔
Explanation

English channel, French La Manche, narrow arm of the Atlantic Ocean separating the southern coast of England from the northern coast of France

and tapering eastward to its junction with the North Sea at the Strait of Dover

The English Channel is the world's busiest shipping route, serving over 500 ships daily.