Chat Moss is a large area of peat bog that makes up part of the City of Salford, Metropolitan Borough of Wigan and Trafford in Greater Manchester, England. It also makes up part of Metropolitan Borough of St Helens in Merseyside and Warrington in Cheshire. North of the Manchester Ship Canal and River Mersey, 5 miles (8 km) to the west of Manchester, it occupies an area of about 10.6 square miles (27.5 km2).