The Blue Stack Mountains or Bluestack Mountains, also called the Croaghgorms (Irish: na Cruacha Gorma, meaning "the blue stacks"), are the major mountain range in the south of County Donegal, Ireland. They provide a barrier between the south of the county, such as Donegal Town and Ballyshannon, and the towns to the north and west such as Dungloe and Letterkenny.