Baie d'Authie is a kitesurf spot on the estuary of the Authie river (Pas-de-Calais/Somme border), between Berck-sur-Mer and Fort-Mahon-Plage. The bay offers a natural tidal environment with vast sand flats at low tide and a wide open beach.

Best winds are from South-West to West and North-West, blowing across the open bay. Large tidal range — the bay empties considerably at low tide, revealing huge flat sandy areas ideal for kitesurfing. A natural and uncrowded spot on the Côte d'Opale.