The drowning of five family members off Buncrana pier will be recalled at a first anniversary Mass this evening.
Some of those who tried to rescue the family in the Co Donegal seaside town on that Sunday evening have spoken of their sadness.
"There was a communal sense of grief and shock that night," said local priest Fr John Walsh (68), who anointed the victims.
"A silence descended on the town that lasted several days."
The family drowned soon after 7pm when their car slid down the algae- covered slipway into the harbour.
It is thought that the driver, Sean McGrotty, was trying to do a three-point turn at the end of a family a day out.
His partner, Louise James, was the only member of the family who did not travel with them from their Derry home.
Those who died were Mr McGrotty (49), the couple's sons Evan (8) and Mark (12), Ms James' sister Jodie Lee Daniels (14) and her mother Ruth Daniels (57).
Seconds before the car sank beneath the waters of Lough Swilly, Mr McGrotty succeeded in passing the couple's baby daughter Rioghnach through the car window to Davitt Walsh, who bravely swam out to the sinking vehicle.
Although he received several awards for his courage, Mr Walsh remained a modest hero.
In a statement, the family said they were "deeply grateful for the prayers and support over the last year".
Today's anniversary Mass will be offered in the Holy Family Church, Ballymagroarty, Derry, at 7.15pm.
They said a walk in memory of all five members of the family will take place on Friday, also in the city.
Evan had muscular dystrophy, and all money raised will go to research into the illness.
It is thought the victims may have parked on the slipway to watch the sunset after their day out.
Local couple Francis Crawford (67) and his wife Kay heard the shouts for help from Mr McGrotty as the vehicle began to slip into the water. Mr Crawford called 999.
When the couple were contacted, they said they remembered the victims "with sore hearts" and paid tribute to the emergency services.
"It seems a short year since the tragedy, but we feel it will take a long time for the wounds to heal," said Mr Crawford.
Fr Walsh said he arrived at the pier that night and was immediately asked to administer the Last Rites as four of the bodies retrieved from the waters lay on the pier.
"I had just finished anointing the four bodies when they brought the body of the final victim," he said.
"It was a dark night. There was a floodlight from a helicopter beaming down when I was anointing. I just whispered the prayer.
"The saving of the baby was a little miracle. Consciousness of the courage of Davitt Walsh has been with me all year."
Lough Swilly lifeboat service volunteers John McCarter and Joe Joyce said their team went into action immediately.
The multiple loss of life made it "our worst day ever", said Mr McCarter.
Mr Joyce said: "We train for different scenarios, but you never think of something like this."