Croaghgorm, Mountain summit in County Donegal, Ireland

Croaghgorm (Irish: An Chruach Ghorm, 'the blue stack') is a 674-metre mountain in County Donegal, Ireland, and the highest of the Blue Stack Mountains, also called the Croaghgorms. It is the third-highest mountain in the county. Wreckage from a crashed aircraft still lies on its slopes.

On 31 January 1944, a Royal Air Force Sunderland flying boat of 228 Squadron crashed on Croaghgorm's slopes during World War II, killing seven RAF crewmen. Wreckage from the aircraft can still be seen on the mountain, and a memorial plaque was unveiled in 1988.

The name Croaghgorm comes from the Irish An Chruach Gorm, 'the blue stack'. The same Irish name supplies the alternative English form Bluestack, and the plural Croaghgorms is used for the whole range, of which this is the highest top.

The climb is best approached from one of the main entry points such as Barnsmore Gap or Edergole Farm, depending on your preferred direction. The terrain varies between rocky sections and grassland, so sturdy footwear and caution in changing conditions are advisable.

From the summit, the views sweep across southern Donegal and on clear days reach toward the distant hills of Sligo and Leitrim. This expansive outlook reveals how the range connects to other mountain regions across the wider landscape.