From the hills of Artois, the Authie (100km) joins the Channel via the Baie d'Authie, south of Berck. From Gennes-Ivergny to the coast (50km), the river demarcates the border between the Somme and Pas-de-Calais. Springs, bocages, prairies, poplars, pollarded willows, marshes, hills, squat whitewashed houses… The Authie has carved out a bucolic valley in the chalky plateau. Visiting Valloires Abbey and strolling in its grounds is an inviting prospect, as is a trip to the Moulin de Maintenay, a pretty watermill in a village with a basket-making tradition and some good inns.