The Derwent is a river in Yorkshire in the north of England. It flows from Fylingdales Moor in the North York Moors National Park, then southwards as far as its confluence with the River Hertford then westwards through the Vale of Pickering, south through Kirkham Gorge and the Vale of York, joining the River Ouse at Barmby on the Marsh. The confluence is unusual in that the Derwent converges on the Ouse at a shallow angle in an upstream direction. The old course of the river used to flow further east, entering the Ouse east of Howden.