Ferguson, of Christchurch, cut a solitary figure around the course and was unstoppable to lead from start to finish in the women's race.
She powered away on the bike, after exiting the 3.8km swim in second place overall, to blitz her own course record by more than 5min.
There was daylight between Ferguson's winning performance and the next female athlete.
To the delight of the local crowd, Wanaka triathlete Merryn Greenwood was the second woman home, in a time of 10hr 3min 17sec, improving on her fourth result from last year.
A decisive break on the 180km cycle, between Tarras and Lake Hawea helped push Chris McDonald to victory, although the big Australian privately doubted whether he could hold on to his lead through the 42km run.
McDonald was second last year, when he was run down on the final leg by Germany's Marc Pschebizin, after leading off the bike.
The men's race was a riveting combination of endurance, speed, and determination - especially from McDonald.
He exited the swim, more than 2min behind the leaders, and unleashed his frustration in a powerful performance on the bike.
Within 30km of climbing into the saddle, he had caught up with the leading bunch.
McDonald said he pushed himself extra hard for the first 80km on the bike.
He led a bunch, which consisted of Justin Daerr (USA), Keegan Williams (NZ), and Petr Vabrousek (CZE), through to Cromwell at an average bike speed of 40kmh.
The group turned north into a strong headwind and rode back alongside Lake Dunstan.
McDonald and Daerr, training partners for the past six months, made their break shortly after the turn-off, near Tarras, in what proved to be a turning point in the race.
The pair worked together to establish a lead through to Lake Hawea, where they turned again to receive a helping tailwind on the return to Wanaka.
McDonald came into the transition area with a lead of 4min over Daerr, who recorded the fastest overall bike time on the day of 4hr 45min 17sec - a cycle leg record.
McDonald said he wanted a healthy lead over chasing Czech, Vabrousek.
"I like to race at the front and don't want to hold back," he said.
However, he admitted to doubts as to whether he had done enough on the bike to hold off the chasers - especially Daerr.
"He's got a good run on him and I was worried about my splits," McDonald said.
Daerr looked fresh as he came into the first lap of the run, while McDonald, by comparison, was walking the demanding hill climbs of Gunn Rd, near the back of the course.
"I've timed those hills in training and you can power walk them as quick as you can run.
"Your heart rate goes through the roof otherwise," he said.
His strategy worked, as Daerr's efforts on the bike took their toll and he fell off the pace, to the delight of young Hamiltonian Keegan Williams.
Williams, who had held on to a slight advantage over Vabrousek off the bike, passed the American, about 20km in and held on grimly to claim second place in a time of 8hr 44min 8sec.
Vabrousek also bypassed the fading Daerr to place third as he vainly tried to close the 30sec-deficit to Williams.
Meanwhile, McDonald kept on increasing his lead and by the 32km mark had a 7min-buffer.
He settled into a steady pace and slashed 10min off the course record to a jubilant welcome from a boisterous Wanaka crowd.
