The little sister of the Authie River, the Canche is a slow-flowing river whose waters run into a marsh. In this untamed setting, the green valley broadens out into gentle slopes scattered with elongated houses with whitewashed walls. Between Touquet-Paris-Plage and Hesdin, don't miss the ramparts of Montreuil and the Notre-Dame-des-Prés Monastery. In Frévent, the Wintenberger Museum revisits the hard labour endured by the peasants and workers of Ternois. The Canche ultimately flows into the Côte d'Opale in Étaples.