Between the beachside towns of Berck-sur-Mer and Merlimont there are a series of smaller bunker complexes designed to defend the areas between major gun batteries.
This one, aptly named Wn20 'Bunker', features just one large gun casemate - a R612 type for a 7.5cm field cannon plus two R600 ringstand open emplacements for 5cm KwK anti-tank guns with small ammunition stores, two shelters, and a Tobruk for a captured tank turret.
It was closely linked with several other smaller sites along the long stretch of beach.