The incident happened off Wexford's Hook Head this evening.
The father of four in his forties was taking part in an underwater search for a fisherman who went missing from a trawler off the Saltee Islands yesterday morning.
The alert was raised shortly after noon today as he returned to the surface after a dive.
He was treated by colleagues at the scene and airlifted to University Hospital Waterford where he has since been pronounced dead.
Teen M9 Fatalities Were Known To Gardai in West Wicklow
The 15 to 18 years old had been involved in several road incidents locally in recent weeks.
Talented Wicklow Pair Shortlisted for National AIB Portrait Prize
Bray photographer Alannah Henry and Donard-based teenage artist Isla Case were named among a combined 46 shortlisted entries, selected from hundreds of submissions from across the country
Wicklow Rose Ready To Bloom On TV Screens Tonight
Carolann McDonald will appear in tonight's second Rose of Tralee live show.
'Nothing Is Off The Table' - Wicklow TD Outlines Concerns Over Planned Fuel Excise Increases
Concern Grows For Missing 53-year-old
Sean Gaughan has now been missing for two weeks
Light rain shower
High: 20°C | Low: 12°C
Light rain shower
High: 20°C | Low: 13°C
Light rain shower
High: 20°C | Low: 12°C
Light rain shower
High: 19°C | Low: 11°C
Light rain shower
High: 20°C | Low: 12°C
