Glen Tanar (Scottish Gaelic: Gleann Tanar) is a glen in Aberdeenshire, eastern Scotland, through which the Water of Tanar flows. Near the mouth of the glen, at Tower o' Ess, the Water of Tanar flows into the River Dee. This flows through Deeside into the North Sea at Aberdeen. Glen Tanar contains the third largest area of Caledonian Forest in Scotland, and is of national and European importance. It is around 18 miles East from the Queen's private residence at Balmoral Castle.