The River Key is a tributary of the River Thames in England which flows through Wiltshire.The river rises at Braydon Forest near Purton and runs through Purton Stoke, joining the Thames on the southern bank near Cricklade just upstream of the A419 Road Bridge. The river was crossed by the North Wilts Canal a few hundred yards south of Cricklade on the B4553 to Purton. In December 2000, as part of regeneration of the canal, rescue work was started on the River Key Aqueduct.