The Health and Safety Authority (HSA) is investigating the death of a man during work on pontoons in the south Connemara harbour of Ros-a-Mhíl on Sunday evening.
The man, who was in his 40s and believed to be from the north west, was working on installation of the pontoons when he was struck on the head by a piece of industrial equipment.
A second man was also hurt, but his injuries are described as not life threatening.
The Irish Coast Guard administered first aid at the scene, and the seriously injured man was flown to University Hospital, Galway by the Shannon-based Sikorsky air/sea rescue helicopter. He was pronounced dead later on Sunday evening.
The HSA said it was aware of the incident and was sending an inspector to the location on Monday.