Dentdale is a dale or valley in the north-west of the Yorkshire Dales National Park in Cumbria, England. It is the valley of the River Dee, but takes its name from the village of Dent. The dale runs east to west, starting at Dent Head, which is the location of a railway viaduct on the Settle-Carlisle Line. Dentdale is one of the few Yorkshire Dales that drain westwards to the Irish Sea.