Teesdale is a dale, or valley, in Northern England. The dale is in the River Tees’s drainage basin, most water flows stem from or converge into said river, including the Skerne and Leven.

Upper Teesdale, more commonly just Teesdale, falls between the Durham and Yorkshire Dales. Large parts of Upper Teesdale are in the North Pennines AONB (Area of Outstanding Natural Beauty) – the second largest AONB in England and Wales. The River Tees rises below Cross Fell, the highest hill in the Pennines at 2,930 feet (890 m), and its uppermost valley is remote and high. The local climate was scientifically classified as “Sub-Arctic” and snow has sometimes lain on Cross Fell into June (there is an alpine ski area Yad Moss).

Lower Teesdale has mixed urban (Tees Valley or Teesside) and rural (Cleveland) parts. Roseberry Topping is a notable hill on the south eastern side, of which this and other adjoining hills form the northern end of the North York Moors.

Newer terms have gained stronger associations with separate parts of the valley due to their use as specific political constituencies and authorities.