Ravensbourne is a tributary of the River Thames in South London
. It flows into the River Thames on the Tideway at Deptford, where its tidal reach is known as Deptford Creek.The Ravensbourne is 11 miles (17.4 km) in length with a total catchment area of 180 km2. It flows through the London Boroughs of Bromley, Lewisham
The Ravensbourne rises at Caesar's Well, Keston, four miles south of Bromley town centre, flowing initially in a northerly direction. For the initial third of its length the river flows across common land (including Hayes Common and Bromley Common) until it reaches the southern outskirts of Bromley town where it is joined by the Ravensbourne South Branch and the Ravensbourne East Branch, that substantially increase the flow.