The river Canche (Dutch: De Kwinte) is one of the rivers that flow from the plateau of the southern Boulonnais and Picardy, into the English Channel. The Somme is the largest example. The basin of the Canche extends to 1,274 square kilometres (492 sq mi) and lies in the southern end of the département of Pas-de-Calais. Forming an alluvial valley from 1 to 2 kilometres (0.6 to 1.2 mi) wide, the Canche is a verdant landscape of calm waters, marshes, meadows and small woods.