DEE, a river of England, rising in Bala lake, Merioneth-shire. In the first part of its course, which lies through the beautiful valley of Llangollen, its current is exceedingly rapid. After passing Wynnstay it turns northwards, and forms the boundary line which separates Denbighshire from Flintshire and Cheshire. In its after course it runs wholly within Cheshire. After nearly encircling the city of Chester, it is continued by an artificial channel for about nine miles until it falls into a spacious tidal estuary, which at its communication with the sea is nearly six miles wide. Its principal tributary is the Alwyn, which joins it at Holt. Its whole course is upwards of 70 miles in length.