WATERLOO-WITH-SEAFORTH, a watering-place of Lancashire, England, on the Irish Sea, at the mouth of the Mersey, nearly opposite New Brighton in Cheshire, and on the Liverpool, Crosby, and Southport Railway, 4 miles north by west of Liverpool. On account of its facilities for bathing, firm sands, pleasant scenery, and nearness to Liverpool, of which indeed it may now be considered a suburb, it is much frequented during the summer months. It is well and regularly built, and possesses the usual characteristics of a rising watering-place. The population of the urban sanitary district (area 740 acres) was 9118 in 1881.