The River Neckinger is a reduced subterranean river that rises in Southwark and flows approximately 2.5 kilometres (1.6 miles) through south London to St Saviour's Dock where it enters the Thames. What remains of the river is enclosed and runs underground and most of its narrow catchment has been diverted into other combined and surface water sewers, flowing into the Southern Outfall Sewer and the Thames, respectively.