Croaghgorm or Bluestack (from Irish: an Chruach Gorm, meaning 'the blue stack') is a 674-metre (2,211 ft) mountain in County Donegal, Ireland. It is the highest of the Blue Stack Mountains (or Croaghgorms) and the third-highest mountain in County Donegal. On 31 January 1944, during World War II, a Royal Air Force (RAF) Sunderland plane crashed on the mountain. Seven RAF crewmen from 228 Squadron were killed. Wreckage from the plane can still be seen on the mountain's slopes. A memorial plaque was unveiled in 1988.