The Ouse is a river in England that joins the Trent. It is a tributary of the Humber Estuary and is approximately 80 miles long. The source of the Ouse is in the North York Moors National Park, and it flows through the Vale of York and the city of York before joining the Trent. The Ouse is an important waterway for navigation, and it is also used for recreational activities such as fishing and boating.