The confluence of the Rivers Glanduin and Gwathló formed this swamp in Cardolan to the east of Tharbad. Numerous swans made the marshes their home, giving the region the Westron name Swanfleet .The four hundred square miles of the Swanfleet Marshes just outside of Tharbad, harbored treacherous alkali bogs and innumerable poisonous reptiles. The Cardolandrim and Dunmen both braved the fens in search of rare herbs, but more often the intent was to poach the lordly swans gracing the waters. Their feathers were highly favored by the fashionable ladies of Gondor, and were the only dependable source of wealth to be found locally.