A special mass and wreath laying ceremony takes place this morning to mark one year since Rescue Helicopter 116 crashed off the Mayo coast.
All four crew members were killed when the chopper went down near Blackrock Island in the early hours of March 14th 2017.
Late last night, up to 100 people attended a vigil to remember Dara Fitzpatrick, Mark Duffy, Paul Ormsby and Ciaran Smith.
The bodies of Captain Dara Fitzpatrick and Captain Mark Duffy were recovered in the days following the crash, but their colleagues Paul Ormsby and Ciarán Smith remain lost at sea.
Local Superintendent Tony Healy says the tragedy had a huge impact on the community.
He explained: "They felt it very much as a personal loss - as if it was one of their own families, or one of their own friends, that had been lost at sea.
"You can really see that in the huge, mammoth effort over the long duration of the 50 days of the search - they were as resilient at the start as they were at the end."