The Five Rivers plain, surrounded by numerous peaks and mountain ranges, is the catchment base for the five rivers: Irthing, Cromel, Acton, Oswald, and Dilston, named in the 18th Century by the chief surveyor for Otago, J.T. Thomson from rivers back in his home county of Northumberland. These rivers in turn feed the Oreti River, which begins its own journey in the Eyre Mountains before winding southwards past Lumsden and finally discharging into the New River estuary near Invercargill.