The river Canche is one of the rivers that flow from the plateau of southern Boulonnais and Picardy, into the English Channel, of which the Somme is the largest example. It is 100.2 km (62.3 mi) long. The basin of the Canche extends to 1,274 square kilometres (492 sq mi) and lies in the south of the département of Pas-de-Calais. Forming an alluvial valley from 1 to 2 kilometres wide, the Canche valley also contains marshes, meadows and small woods. The gentle gradient, averaging 1.5 percent, gives the river a meandering course.

The Pas-de-Calais is a department in northern France named after the French designation of the Strait of Dover, which it borders. It has the most communes of all the departments of France, with 890, and is the 8th most populous. It had a population of 1,465,278 in 2019. The Calais Passage connects to the Port of Calais on the English Channel. The Pas-de-Calais borders the departments of Nord and Somme and is connected to the English county of Kent via the Channel Tunnel.