The Vale of Clwyd (Welsh: Dyffryn Clwyd) is a tract of low-lying ground in the county of Denbighshire in northeast Wales. The Vale extends south-southwestwards from the coast of the Irish Sea for some 20 miles (about 30 km) forming a triangle of low ground bounded on its eastern side by the well-defined scarp of the Clwydian Range and to the west by numerous low hills. The River Clwyd (Welsh: Afon Clwyd) which rises within Clocaenog Forest, southwest of Denbigh, runs the full length of the vale. It is joined by the two major left bank tributaries of the River Clywedog (Welsh: Afon Clywedog) and River Elwy (Welsh: Afon Elwy) and the smaller right bank tributary of the River Wheeler (Welsh: Afon Chwiler).