river that rises near Wearhead in the county of Durham, England, and enters the North Sea at Sunderland. With headwaters in the Pennines, it flows through Weardale and once entered the sea in the vicinity of Hartlepool, but it was subsequently diverted northward. Durham city is built along the Wear, and its castle and cathedral stand 100 feet (30 metres) above the river on an incised meander (loop). From Bishop Auckland the river flows across coalfields, but coal mining had ceased by the end of the 20th century.