High Quality Content by WIKIPEDIA articles! The River Wandle is a river in south-east England. The names of the river and of Wandsworth are thought to have derived from the Old English "Wendlesworth" meaning "Wendle`s Settlement". The river runs through southwest London and is about 9 miles (14 km) long. It passes through the London Boroughs of Croydon, Sutton, Merton, and Wandsworth to join the River Thames on the Tideway at Wandsworth.