It was one of those majestic blue days that come at the end of an Irish summer. After days of grey dreariness and rain, the sun finally came out at Mullaghmore, casting a shimmering glow on the sea.
But by the end of that morning on August 27, 1979, the sky would be filled with an orange flash, and a shower of emerald-green splinters. The sea would be streaked with blood.
A member of Britain's royal family and two children would be dead -- and an elderly grandmother would later join them on the list of fatalities.
Until that moment in history, Mullaghmore in Co Sligo was known as a pretty fishing village and holiday resort, with a golden strand that never seemed to end.
Ben Bulben, Sligo's spectacular table mountain, looms on the horizon on one side, and the hills of Donegal can be seen on the other.
On good days in the 1970s it could be packed with holidaymakers, many from the North and Britain.
And then of course there was the royal adornment, Lord Louis Mountbatten, former imperial potentate, who spent his summers on the hilltop at Classiebawn Castle, a spooky Victorian edifice that could be the home of Dr Frankenstein.
As the sea shone like a jewel, ponies carried a few remaining children along the beach. Lobster fishermen pottered around the little harbour as Mountbatten and his party left Classiebawn Castle in a white Ford Granada to board his boat, the Shadow V.
They were followed by two plainclothes gardai in an unmarked car as they made the short journey to the harbour.
In hindsight, the security provided seemed merely tokenistic. This, after all, was Earl Mountbatten, former ruler of India and a senior member of the royal family -- and it was the height of the vicious sectarian war, quaintly known as the Troubles.
While he did have a garda escort, nobody was guarding his boat, which was moored in the harbour. Planting a 50lb gelignite bomb under the engine in the dead of night was a piece of cake for an experienced terrorist force.
When Mountbatten boarded the emerald-green vessel, no bodyguard joined his party.
"He didn't like too much security around him on holiday,'' Mountbatten's friend Rodney Lomax told me this week in his boatyard close to the Mullaghmore seashore. "This was somewhere where he liked to relax and be quite casual.''
Rodney Lomax looked after the Shadow V, ensuring that it was always ship shape, just as the former naval commander wanted.
"He liked to do everything as if it was a major naval operation, even if he was just cornering a shrimp.
"Lord Mountbatten asked me to go out on the boat that day, because something needed to be fixed,'' said Rodney Lomax. "But I didn't go, because I was taking my children on holiday in Cavan. You wouldn't normally say 'no' to Mountbatten, but I did on that day.''
Boarding the boat soon after 11 in the morning, Mountbatten assembled his shipmates for a family photo. With him that day were members of his daughter's family, including two 14-year-old twin boys, Timothy and Nicky Knatchbull.
Some of the other members of the family stayed behind and watched a Laurel and Hardy film on television, while another was delayed in the village when he bought cigarettes.
Paul Maxwell, a 15-year-old from Enniskillen, helped out on the boat that day. As much as Mountbatten and any of the other victims, he is fondly remembered in the village.
As the boat chugged out, the garda escort slowly motored up a cliffside road keeping an eye on the sea. Somewhere close by, an IRA member also looked on, ready to detonate an explosion.
Mountbatten's boat was only a few hundred yards into Donegal Bay when the entire neighbourhood heard a massive bang. Windows shook in houses miles away as the bomb ripped the vessel apart. Witnesses described an orange flash, a shower of sea spray, and green fragments.
Peter McHugh, whose family has run the Pier Head hotel for generations, told me how he was just standing next to the hotel when he heard the bang. "I thought it was a gas cylinder exploding. But then I knew something very serious had happened when I saw the garda car coming speeding back into the village.'' Peter then jumped on to a boat and headed out into the bay. He was among the first to reach the scene of the explosion.
"It was a terrible sight. Bodies were being recovered from the water, and the injured were being pulled out.''
Mountbatten and the youngsters, Nicky Knatchbull and Paul Maxwell, were killed instantly.
Minutes later on the shore, Paul's father, John, who still holidays in Mullaghmore, looked down on his son's body and said: "Look what you've done to him, look what you've done to him. I'm an Irishman, he's an Irishman. Is this the sort of Ireland you want?''
The explosion left Tim Knatchbull floating almost lifeless on the water. Fortunately for the survivors, the warm weather ensured that there were boats in the area that came to the rescue.
Tim was plucked from the sea unconscious. His eyes were scorched and his lungs were filling with blood.
He was taken to Sligo General Hospital along with his parents, Lord John and Lady Patricia Brabourne, who were also both seriously injured. Later, the news was broken to Tim that his twin, Nicky, had been killed. His grandmother, the dowager Lady Brabourne, also perished.
In one of the most moving accounts of the murders, Mountbatten's daughter Patricia Brabourne recalled coming round in Sligo Hospital for the first time, days after the blast.
In A Heartbeat Away, a book produced for the Child Bereavement Trust, she said, "All I could remember of the explosion was seeing a ball of light, about the size of a tennis ball, radiating out from beneath my father's feet.
"Then I was in the water, turning over and over. I was certain I was going to drown.''
Mountbatten's daughter kept praying to herself: "The boys must be all right -- they have to be.''
When she came to, Tim was in intensive care with her. So she knew within a short time that he had survived, but what about Nicky? She finally summoned up the strength to scribble Nicky's name on a piece of paper, and was told that he had not survived.
"It was overwhelming. I tried to cry but could not even do that since the pain of the stitches round my eyes prevented me. I felt desperate -- as if a part of myself had died with my son."
Patricia Brabourne said the nurses in Sligo hospital were so ashamed of what their countrymen had perpetrated -- the murder of two old people and two innocent boys -- that they found it almost impossible to look her in the face. "I have never blamed the Irish people for what happened,'' she said.
The murders not only brought grief to the Mountbatten and Maxwell families, it also cast a long shadow over Mullaghmore.
Soon after the blast, the Sunday Independent reporter Frankie Byrne suggested that the village was "transformed into a morgue-like trance''. In a way, Mullaghmore has never woken up from that trance.
Tourism numbers dropped off rapidly. For a time, visitors from the North and Britain stopped coming -- and many never returned.
Returning to the village 30 years afterwards, one is struck by how little has changed.
Rodney Lomax still runs his boatyard opposite the sailing club. He has fond memories of Mountbatten, but was well aware of his foibles.
"He could be very overbearing and had very fixed ideas about how things should be done, but he was well liked locally.
"I was up in the castle on the night before the explosion. He didn't drink himself, but he had a liberal hand and he made sure the butler filled our glasses."
Rodney Lomax talks of Mountbatten, a man who had lived for 79 years, with jocular affection, but his voice trembles at the mention of Paul Maxwell, the 15-year-old boat boy, and Nicky Knatchbull.
Nicky's brother Tim, whose book on the murders From A Clear Blue Sky will be published next month, has called in to see the Lomaxes on quiet, unpublicised visits.
There is no memorial to the victims in Mullaghmore, but Mountbatten's castle, now owned by the businessman Hugh Tunney, stands as a monument on the hill.
Visitors stop at the gates of the castle. There, on the gate post the Mountbatten crest remains with the ancient French motto -- Honi soit qui mal y pense -- Evil be to him who evil thinks.