Showcasing Bay's young talent was the under-19 team, who finished second to Gisborne, following wins by the under-16s and a runner-up placing by Bay of Plenty under-14.
Harman's progress in an eventful last 12 months - following his shock sprint victory New Zealand championships - has stunned world champion beach flagger Paul Cracroft-Wilson, who was part of the winning Taranaki team.
"He's unbelievable. The times he's posting on the track and the age he is ... he's only just going to keep getting faster," Cracroft-Wilson said.
"He's got a massive future and it's great for the rest of us because it makes us work harder to keep there. If I can match him or get close in sprint, I know I'm going well and I've just got to keep that little bit of an edge in the flags."
Cracroft-Wilson only just edged Harman in yesterday's flags, with the Bay flyer finishing fourth.
Nothing could deny Taranaki overall, despite being unfancied before the event.
"We've built a winning culture and we went in there this weekend as a little bit of an underdog," Cracroft-Wilson said.
"We had the belief and we had the crew - a nice mix of experience and youth - and deep down, we knew we were going to come out on top again. It means a lot and because of all the talk going into it, this is probably the best of the four wins."
Taranaki collected 251 points from the 36 open events. Gisborne won the carnival-ending Dearlove relay to finish second on 240, edging Auckland who finished on 236.
Once again, Taranaki's team culture proved insurmountable, with New Zealand team members Glenn Anderson, Cracroft-Wilson and Ayla Dunlop-Barrett adding the sparkle to an all-round effort.
IRB guns Andrew Cronin and James Morwood won all four of their races while the canoe crew were also exceptional.
Halligan's efforts were just as special, winning all four ironwoman races - two in the under-19s and two in the open - over the weekend, helping Gisborne win the under-19 title.
The daughter of former Kiwis rugby league player Daryl Halligan needed sprint finishes each afternoon to get past New Zealand star Nikki Cox.
"I was a bit unfit going into the Aussie titles in a few weeks but this weekend has definitely sorted me out," Halligan said. "I'm stinging now but it's great to get some good racing in going into the pointy end of the season."
She was nearly matched by 17-year-old Gisborne schoolboy Cory Taylor, who won both his under-19 races and added a win in the open yesterday. Fellow Gisborne athlete Oliver Puddick - drafted into the Wellington team for the event - won yesterday's ironman from Auckland's Chris Moors.
Taylor explained the heavy workload eventually took its toll.
"I'm quite happy with that - I was hoping to get four from four but my swim leg was a real struggle in that last one," Taylor said. "I just couldn't seem to keep up with the pace at the start and had to play catch-up.."
Auckland's Chanel Hickman grabbed the women's beach flags and beach sprint double, while Cracroft-Wilson looked set for another flags title but false-started in the final, handing the win to New South Welshman Blake Drysdale. New South Wales finished fourth, edging past hosts Bay of Plenty in the last relay, with Hawke's Bay sixth.