The River Ouse is formed by the junction of the River Ure and River Swale. The river flows south through York to its junction with the River Trent, where it becomes the Humber. Total length of the river is 52 miles (100 miles for the combined Ouse/Ure). The Ouse's tributaries (which includes the Derwent, Aire, Don, Wharfe, Rother, Nidd, Swale, Ure, and Foss) drains a large upland area of Northern England, including much of the Yorkshire Dales and North York Moors. Wikipedia: Link