He told the congregation that his father had been a “great man” who worked hard and said that people should enjoy their time together and the gift of life.
Hamish said: “I am grateful for all the people who have come here today. I would just like to say a few words about my dad.
“He was a great man. He worked very hard and very long each day. Whether it was around the house or at work.
“He wore a jacket with a huge paint stain on the side of it everywhere.
“He managed this by leaning on a wall which was still wet with paint.
“He wore the jacket everywhere. To the shops, to the movies, to the beach.
“I would like to say thank you to all of the people who have given and offered so many things.
“The emergency services too, who were there within 15 minutes and also came to the wake.”
Hamish also told the congregation: “I would also like to say something I have learnt in the past week or so.
“We should be grateful. For your families, cherish them, be grateful for they won’t be there forever.
“Use the time you have wisely.
“Also, be grateful for your life because that too will not last forever.
“Be grateful, for you will be able to rest after your hard work.”
As he stepped down from the altar there was a standing ovation from those in the church.
Ten people, aged from five to 59, were killed in the tragedy in the Co Donegal village.
The Requiem Mass for Mr O’Flaherty took place at Teach Pobail Mhuire in the Gaeltacht village of Na Doirí Beaga.
The 48-year-old engineer, originally from Sydney, had been living in Dunfanaghy with his wife and son.
When the cortège arrived, pupils of Faugher National School, which Hamish attends, provided a guard of honour as his remains were brought into the church.
Gifts were brought up at the beginning of the Mass to reflect his life.
They included a Roald Dahl book ‘Going Solo’, which he and his son had been reading together.
A box of chocolates was also brought up to reflect Mr O’Flaherty’s sweet tooth and placed alongside a framed family photograph.
Parish priest of Gaoth Dobhair An t-Athair Brian Ó Fearraigh told mourners that Mr O’Flaherty was “a truly amazing father, a loving husband, a committed work colleague and a dear friend to many”.
He said Mr O’Flaherty “showered his lovely son Hamish with kisses and hugs every day. He was so proud of Hamish and he had every reason to be.”
An t-Athair Ó Fearraigh said everything Mr O’Flaherty did was for his wife Tracey and for Hamish and they were “inseparable as a family”.
He said he loved cooking “crazy omelettes and curries” and that he would eat curries “until they came out his ears”.
Mourners were told that Mr O’Flaherty was a man who had high morals.
“He was a man of honour and his word was his bond,” An t-Athair Ó Fearraigh said.
He said: “We have all experienced since Friday afternoon that grief knows no boundaries.
“The tragic event and the effects of the Creeslough catastrophe, which is beyond comprehension, knows no bounds.
“The intensity and the awfulness of the tragedy has reverberated near and far. Away beyond the shores of this beautiful country of ours.
“The outpouring of support and messages of condolence and offers of help that we have heard and witnessed, all has been overwhelming.
“Parochial, county, country boundaries have been crossed. Hands of support and friendship have been offered.
“In crossing such boundaries we have seen how from the shadow and out of the depths of the darkness of this terrible tragedy a most beautiful and radiant and divine light of friendship, love and support has shone and continues to shine brightly.”
Speaking to Tracey and Hamish, An t-Athair Ó Fearraigh said the things that bring us to “our knees” can also be the things that bring us close to one another and to God.
At the end of his homily, he gave a set of rosary beads to Hamish.
Mr O’Flaherty will be buried at Magheragallon Cemetery.
President Michael D Higgins attended the funeral, as he will do again later today at the funerals of Catherine O’Donnell and her 13-year-old son James Monaghan in Creeslough.
Speaking afterwards he praised those who responded to the tragedy both at the time and in subsequent days.
“I think it’s very important what’s being revealed now in the response of the public and the response of the people of Creeslough and that great example they’re giving us.
“They have a very heavy burden of grief and there’s no point in saying anything other than that.
“I think the way they are holding together is a great example to us and it’s inspirational, not just in Donegal but all over Ireland how people have been responding and how they’ve been able to reveal their feelings and how their hearts have been broken”.
Over the coming days, President Higgins will meet relatives of those killed in the tragedy as well as members of the emergency services.
Yesterday hundreds of people turned out to pay their respects at the funerals of 24-year-old Jessica Gallagher and 49-year-old Martin McGill.
Parish priest Fr John Joe Duffy said that while hearts are heavy in Creeslough, “spirits are strong”.
Funerals will continue to take place for the rest of the week in communities across northwest Donegal.
Books of condolence have been opened in towns and cities across Ireland.
Additional reporting: Sinéad Hussey, PA