Sligo-based coast guard helicopter Rescue 118 assisted in a major multi-agency operation on Friday afternoon.
The alert was raised after there were reports of three divers in difficulty a mile south of Inishbofin.
Clifden RNLI were first on the scene with their Atlantic 85 lifeboat.
Alongside the dive boat, they escorted the group back to Inishbofin pier.
From there, the lifeboat crew and members of the local community helped the divers to the airstrip on the Island where they were airlifted by Rescue 118 to University Hospital Galway for hyperbaric treatment.