Cockermouth /ˈkɒkərməθ/ is an ancient market town and civil parish in the Borough of Allerdale in Cumbria, England, and is so named because it is at the confluence of the River Cocker as it flows into the River Derwent. The mid-2010 census estimates state that Cockermouth has a population of 8,204, increasing to 8,761 at the 2011 Census.Historically a part of Cumberland, Cockermouth is situated outside the English Lake District on its northwest fringe.