<P> The Strait of Dover ( French : Pas de Calais ) , at the Channel 's eastern end , is its narrowest point , while its widest point lies between Lyme Bay and the Gulf of Saint Malo near its midpoint . It is relatively shallow , with an average depth of about 120 m ( 390 ft ) at its widest part , reducing to a depth of about 45 m ( 148 ft ) between Dover and Calais . Eastwards from there the adjoining North Sea reduces to about 26 m ( 85 ft ) in the Broad Fourteens where it lies over the watershed of the former land bridge between East Anglia and the Low Countries . It reaches a maximum depth of 180 m ( 590 ft ) in the submerged valley of Hurd 's Deep , 48 km ( 30 mi ) west - northwest of Guernsey . The eastern region along the French coast between Cherbourg and the mouth of the Seine river at Le Havre is frequently referred to as the Bay of the Seine ( French : Baie de Seine ) . </P>
what is the average depth of the english channel
about 120 m ( 390 ft )