Honestly, the most beautiful coastline of Flanders is nowadays in France (Cap Blanc Nez used to be Blankenesse).
On the other side of the North Sea (the Western European appendix of the Atlantic Ocean), here called the "Pas de Calais" in French, "Nauw van Kales" in Dutch, and "Strait of Dover" in English, you'll find the notorious white cliffs of Dover, but of course those are no more than a sad copy of the white cliffs of Blankenesse :-)
Anyway, if you're into enormous beaches disappearing under the waves in no time, impressive cliffs, fossiles (though you're not allowed to chop them out of the rocks, you are allowed to pick up loose ones and there's plenty of them), and - of course - photography, Cap Blanc Nez is a nice place to be.
PS: I do not repost all my previous Flickr photos to Photoblog, but ... I have all my photos on another medium too: Pinterest. You'll find all my Cap Blanc Nez-pictures here.