Desmond 'Dessie' Byrne (52) died in a horrific tragedy alongside his 62-year-old Swedish-based sister, Muriel Eriksson, while his teenage son was on Ballybunion beach and is believed to have witnessed part of the incident unfold on Thursday afternoon.
Mr Byrne, who is originally from Athlone, has been based in Lecarrow in Roscommon for many years and worked as a carpenter and carpet-layer.
His older sister had been living in Malmo in Sweden over recent years but maintained very close links to Ireland.
Taoiseach Micheál Martin, who has been visiting Kerry, paid tribute to Mr Byrne and Ms Eriksson.
"We're all deeply shocked and saddened at this very tragic and heartbreaking loss of life on what was a beautiful day,” he said.
"I want to extend my sincere sympathies to the family and friends of those who lost their lives, particularly to those family members who were present and who witnessed this heartbreaking tragedy," he added.
"I want to pay tribute also to our first responders and emergency services who did everything they could as quickly as they could to respond to the emergency that unfolded.
"It reminds us all of how treacherous the seas and oceans can be. But at this point in time our deepest sympathies and hearts are with the people who have been bereaved as a result of this very, very sad tragedy.”
The chairman of Westmeath Co Council, Aengus O'Rourke, was a childhood friend of the Byrnes and said the entire community was numbed by the tragedy.
"When you talk about Dessie Byrne you think of a fun-loving character who always had a smile on his face," Cllr O’Rourke said.
"Dessie loved activity-based holidays. I know he was involved in a cycling club here. He also went swimming. Thirty years ago, when no-one was going skiing, Dessie Byrne was going skiing.
"I just cannot believe he is gone. He was such a multi-talented man. Everyone is numbed by the scale of this tragedy. Like everyone in the community in Athlone I would like to express my deepest sympathies to the Byrne family who are hugely respected here."
Lecarrow Lazers Cycling Club paid a moving tribute to one of their most dedicated members.
"It is with great shock and sadness that we learned of the tragic passing of our dead friend and clubmate, Dessie Byrne, and his sister, Muriel, in a drowning accident yesterday evening," a Laser CC spokesperson posted.
"On behalf of the club we extend our sympathies to Dessie's family, relatives and friends. All the club activities are cancelled for this weekend as a mark of respect."
The siblings - along with Mr Byrne's teenage son - had decided to take a brief Irish holiday including a visit to Ballybunion while his sister was home from Sweden.
It is understood they had only arrived in Ballybunion days before the tragedy.
The distressed teen was located on the beach by emergency services and treated for shock before being reunited later with relatives.
Kerry rescue officials described the tragedy as the worst swimming-related accident in the area for over 30 years.
The two siblings died after getting into difficulty with notoriously strong currents offshore from Ballybunion beach.
The strand is ranked as one of the most picturesque in Ireland but is known for a strong tide and powerful currents which sweep past the north Kerry coast - currents which can prove dangerous to the unwary.
It is believed Mr Byrne and his sister went for an afternoon swim off Ballybunion shortly after 4pm on Thursday.
Mr Byrne's son was playing on the beach at the time.
It is believed the 62-year-old woman got into difficulty while swimming offshore.
Her brother, who was also swimming, is believed to have realised she was in difficulty and bravely went to her assistance.
However, he quickly fell victim to the same currents and also got into difficulty.
The alarm was raised at 6pm when a person on shore spotted what they thought was a man in difficulty in the water.
Mr Byrne's body later washed closer to shore and when emergency services reached the area they recovered him unresponsive from the water.
Despite desperate efforts to revive him, he was pronounced dead at the scene.
There were local concerns that another two people were in the water and a massive rescue operation was triggered.
This involved units of the Irish Coast Guard including the Shannon-based Rescue 115 helicopter, a Kilrush-based RNLI lifeboat, the Ballybunion inshore rescue boat and Ballybunion Sea and Cliff Rescue as well as the north Cork-based Irish Community Air Ambulance.
Gardaí and HSE officials provided shore-based support.
A short time later, the body of Mr Byrne's sister was recovered from the water.
She was unresponsive and, despite desperate efforts to revive her, she was also pronounced dead at the scene.
Rescue officials initially feared that a third person was in the water so the search operation continued for another hour.
Both helicopters remained on standby off Ballybunion in case of an emergency hospital transfer.
However, once it was confirmed there was not a third casualty in the water and Mr Byrne's son was located unharmed on the beach, the operation was stood-down.
Both bodies were later transferred to University Hospital Kerry (UHK) where full post mortem examinations were conducted on Friday afternoon.
Sources said the deaths of both the brother and sister are being treated as tragic accidents with both believed to have drowned.
A file will now be prepared for a Kerry coroner's inquest next year.
Ballybunion locals were reeling from the worst tragedy to hit the popular north Kerry resort for over 30 years.
Fine Gael TD Patrick O’Donovan described the deaths as a “desperate tragedy” and expressed his “sincerest sympathies to the families” of the bereaved and to the people who witnessed the incident.
“From our perspective, here in Co Limerick, Ballybunion is an extension of our own place,” the Limerick TD told RTÉ’s Today with Claire Byrne Show.
“We know this place intimately. Some of my own extended family were in Ballybunion and saw the commotion that unfolded.
“It’s a desperate tragedy. And there’s really nothing that you can put into words to describe the pall of gloom that’s around north Kerry and west Limerick area at the moment.”
Local Sinn Féin councillor Robert Beasley said everyone in Ballybunion was shocked by the tragedy and the loss of life involved.
"It is a heartbreaking thing to happen and our thoughts and prayers go to that poor family," he said.
He was walking on the cliffs outside Ballybunion on Thursday afternoon and spotted what he thought was a training exercise by rescue services with multiple helicopters hovering offshore.
"Someone then told me that there had been a tragic accident. From what I have heard, it appears one of them got into difficulty and the other went in to save them. Only they got into difficulty too."
Local Fine Gael councillor Michael Foley said: “Everybody is shocked by what happened. It’s very tragic.
“We only live in Ballylongford, which is about 12 miles away, and the whole village is shocked here about the sad news.
“Everyone has said how tragic is it and how they feel for the family.”
Over the past 20 years, two people have drowned in the Ballybunion area - one of which involved an accidental fall.
Forty years ago - when Ballybunion's popularity exploded and the huge influx of visitors resulted in a number of tragedies - locals united to form a special volunteer rescue service aimed at supporting and supplementing local lifeguards employed by Kerry Co Council.
It proved an enormous success and, between 1976 and 1986, Ballybunion didn't suffer a single drowning tragedy.
The area now even boasts its own inshore rescue craft.
However, in August 1992, Ballybunion suffered one of its worst tragedies when a 50-year-old father and his ten year old son drowned when they were trapped by fast rising tides and strong currents while exploring a local cave network near Ladies Beach.
Over the past ten years, five children were rescued from near tragedy off Ballybunion's beach in three separate incidents as the combination of strong tides and treacherous currents almost resulted in disaster.
Twice children had to be rescued in the open sea off Ballybunion after being swept out while playing with inflatable boats and toys.
In 2010, two children were rescued when they were swept away.
In 2013, a ten-year-old and an eight-year-old had to be rescued in the open sea after being dragged out by the current while using a ring-buoy.
Three years ago a young boy was rescued after getting into difficulty while swimming.