Tees, river, c.70 mi (110 km) long, rising on Cross Fell in the Pennines, N England, and flowing generally E between Durham and North Yorkshire and through Cleveland to the North Sea. Its upper valley includes the picturesque falls of Caldron Snout and High Force. The lower valley is a major industrial region. The river is navigable through a dredged channel to Stockton-on-Tees.
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