River Tees

The River Tees (/tiːz/) is in northern England. It rises on the eastern slope of Cross Fell in the North Pennines, and flows eastwards for 85 miles (137 km) to reach the North Sea between Hartlepool and Redcar near Middlesbrough.

Geography

The river drains 710 square miles (1834 km²) and has a number of tributaries including the River Greta, River Lune, River Balder, River Leven and River Skerne. Before the reorganisation of the historic English counties, the river formed the boundary between County Durham and Yorkshire. In its lower reaches it now forms the boundary between the ceremonial counties of County Durham and North Yorkshire, while in the highest part of its course it forms the boundary between the historic counties of Westmorland and Durham. The head of the valley, whose upper portion is known as Teesdale, has a desolate grandeur, surrounded by moorland and hills, some exceeding 2,500 feet (762 m). This area is part of the North Pennine Area of Outstanding Natural Beauty.