A 62-year-old Corkman died of a suspected heart attack while hillwalking on Mangerton Mountain in Co Kerry yesterday.
A post-mortem examination is due to get under way shortly at University Hospital Kerry.
The man was one of a group of three climbing the popular mountain yesterday near Devil's Punchbowl when he developed cardiac difficulties.
Valentia Coastguard was alerted just before 1pm, and tasked both Kerry Mountain Rescue and the Shannon based helicopter Rescue 115 to the scene.
However dense fog meant the helicopter could not airlift the man but it managed to land Kerry Mountain Rescue volunteers and paramedics nearby.
The hill walker was stretchered off the mountain but was pronounced dead at the scene.