The river rises at Gouy-en-Ternois and passes Frévent, Hesdin, and Montreuil-sur-Mer before leaving the chalk to flow to the coast between Étaples and Le Touquet-Paris-Plage. Its principal tributaries are the Ternoise, the Planquette, the Créquoise, the Bras de Bronne, the Course, the Dordogne (not to be confused with the Dordogne) and the Huitrepin which all join on its right bank, i.e. to the north of the Canche. The lie of the land means there is no notable tributary from the south until the Grande Tringue, which flows from marshland into the small, dredged estuary.