Arcachon Bay France Bordeaux Great Dune of Pilat. Europes biggest sand dunebr The Dune of Pilat (French: Dune du Pilat, official name),[1] also called Grande Dune du Pilat, is the tallest sand dune in Europe. It is located in La Teste-de-Buch in the Arcachon Bay area, France, 60 km (37.2 mi) southwest of Bordeaux along France's Atlantic coastlines.