Laing died on Saturday, aged 77, after years of ill-health and battles with melanoma, a brain tumour and stomach cancer.
Laing achieved international fame when his star pupil, Danyon Loader, won two gold medals the 200m and 400m freestyle at the Atlanta Olympic Games in 1996.
The pair had an emotional homecoming and were cheered by thousands in a civic reception and ticker-tape parade through the centre of Dunedin.
Laing beamed as his gifted swimmer was famously brought to tears.
Laing later described the day of Loader's 200m freestyle swim in Atlanta as the greatest in his life.
In return, Loader said that, apart from his parents, Laing had been the most influential person in his life.
Ten other swimmers from the Laing stable reached Olympic or Paralympic status.
He was a father-figure at Moana Pool and guided the fortunes and moulded the futures of many national champions and New Zealand representatives.
But Laing was always more than just an elite coach.
He also touched many lives through his learn-to-swim classes at Moana Pool.
It is estimated he taught 31,000 people - children and adults - to swim during his career.
Laing received numerous honours during his long career.
He received an OBE in 1993, was named the Dunedin Citizen of the Year and a life member of Swimming New Zealand in 1996.
He was Halberg Coach of the Year in 1992 and 1996 and was awarded the BNZ Gold Award for Sport in 2002.
He retired from his coaching job at Moana Pool in 2006 and was inducted into the New Zealand Sports Hall of Fame that same year.
He appreciated the many honours bestowed on him.
"I don't know if I deserve it," he said after receiving the CNZM.
"I have worked hard over the years, but didn't set out to get any honours.
"But I have been in the limelight over the years and deem it an honour for myself and my family.
"It is a great honour to be recognised by my peers."
Laing, who had played for Taranaki, also coached rugby for several Dunedin clubs, coached Otago B and was an Otago A selector.
Surf life-saving was also a passion - but swimming was his calling.
He was a disciple of James Counsilman, the great American coach, and referred to his book, The Science of Swimming, as his bible.
For Laing, technique and work ethic went hand in hand.
He taught his swimmers the basics, then he expected them to apply themselves.
They said you could spot Laing swimmers by their style.
And Laing swimmers could attest to the rigorous training regimes devised by the coach.
Counsilman called it "hurt, pain and agony" - for Laing, it was the way to get results.
Not everyone enjoyed it.
Some swimmers couldn't hack the pace, and in 1995 Laing was dumped as New Zealand coach for the Pan Pacific Games, apparently because the athletes struggled to live up to his expectations.
"I think they feel I'm too tough. They seem to think I don't give the swimmers enough input," Laing said.
While Loader's performance in Atlanta in 1996 was the obvious highlight of Laing's coaching career, two occasions spaced four years apart would later allow others to thank him for his own efforts.
In 2002, he received the contribution to coaching award at the Otago Sportsperson of the Year awards.
He was greeted with an emotional standing ovation by the crowd of about 500.
Four years later, he was the subject of a tribute dinner, a "This Is Your Life" celebration of his life and career.
Organiser Paul Allison, the former chief executive of Sport Otago, recalled Laing made a special effort to make it to his evening.
"He was due to have an operation for a brain tumour that week but postponed it," Allison said yesterday.
"He came alive that night. He was recalling all sorts of facts and figures and it was quite unbelievable."
A charity auction at the dinner raised $33,000 for Laing, with Dunedin Mayor Peter Chin paying $5000 for a signed Murray Webb caricature of the swim coach.
Allison, who was in Beijing recently as a commentator at the Olympic Games and arranged for former Olympic bronze medallist Anthony Mosse, to speak to an ailing Laing on the phone, rates Laing one of the greats of New Zealand sport.
"His contribution was immense, there's no question about that," Allison said.
"He's right up there with the best of the New Zealand coaches, people like Arthur Lydiard and Rusty Robertson and Fred Allen and Cyril Walter, in hockey.
"Duncan is known for his international achievements but there's also the fact he probably taught half of Dunedin how to swim. It's hard to comprehend the impact he had on so many generations of Otago people."
It wasn't all plain sailing in Laing's swimming career.
Many felt he was not given due recognition at a national level, and in 2003 his swim school did not have its learn-to-swim contract renewed with the Dunedin City Council.
But his status as a genuinely great coach has never been questioned.
That was obvious last month when the world's greatest swimmer, Michael Phelps, passed on a special message of best wishes to Laing.
New Zealand Sports Hall of Fame chief executive Ron Palenski said Laing stood alone at the top.
"He quite clearly was the best swimming coach New Zealand ever had. He was head and shoulders above anyone else," Palenski said.
"I'm no expert on swimming but the testimony is two Olympic gold medals and a silver medal for Danyon Loader, plus the other New Zealand swimmers he helped.
"To me, he's the Arthur Lydiard of swimming, or the Fred Allen of swimming. You're talking that sort of level, a legend of sport that New Zealand hasn't seen the like of before and probably won't see again."
Palenski recalled the night in Auckland three years ago when Laing was inducted into the Hall of Fame.
"He was overwhelmed and very humbled."
Laing is survived by his wife, Betty, and six children.
