Pointe de Barfleur is at the north-eastern end of the Cotentin peninsula, while the Gatteville lighthouse indicates the north-western limit of the Baie de Seine. Offshore passes the Raz Blanchard, the strongest ocean current in Europe. Rocky bottoms cause eddies, and the formation of marmites (cylindrical cavities) makes navigation difficult even in good weather. Pink granite rocks show on the surface and make the landscape even wilder.