Dallimore, a triathlon coach and veteran of 10 Iron Man contests, won the duathlon last year and was aiming for a repeat - but Saturday's forecast looked good enough for a record, so he borrowed a kayak and changed his entry at the last minute.
Knowing the wind was going to get up later in the day, he put on the pace early in the ride while conditions during the paddle and the final run down Kerikeri River were idyllic.
"I wish I could have taken in the scenery but I was kind of busy," he beamed.
Dallimore said he was definitely coming back next year.
"The record's mine and I know now what I have to do to beat it. It's a shame the field isn't bigger, but the event's still only three years old. It's quite a unique opportunity to go from one side of the island to the other."
Dargaville vet Graeme Ewenson finished second, despite only recently taking up multisport after a "mid-life crisis".
He competed in last year's crossing, making the mistake of running a marathon a week earlier, and the gruelling Coast to Coast in February. Saturday's Northern Crossing was due to have been his swansong.
"But I'm coming back next year. You've got to support these events. I thought I could be on the podium this year if I targeted it and made sure I was fresh, so I'm pretty happy."
The kayak leg, with its still water and low sun, was "gorgeous"; the toughest part was cycling into Kaikohe, when a stiff headwind made him feel he was going nowhere.
Multisport was a great way to see New Zealand and it was good to have a Northland event, he said.
Hugh Allison of Cambridge won the duathlon in just his second event. His first was in Gisborne late last year.
Whangarei Hospital surgeon Chris Seeley, 55, was third in the solo duathlon and the first Northlander across the line.
"It's a lovely course, but it's really hard - it's the length and there's always an easterly wind. You've got to be prepared to compete all day," he said.
Organiser Owen Smith, of Kerikeri Rotary Club, said the event was growing in popularity every year, with this year's entrants from as far away as Australia.
The $7000 raised would go to the Northland Electricity Rescue Helicopter and community youth projects in Northland.
The route started with an 8km run over a brutal hill from Kupe's first landing place at the mouth of the Hokianga Harbour, followed by an 18km kayak from Opononi to Rawene.
From there, the competitors rode 74km by bike to Waipapa.
A karakia by kaumatua John Klarisich preceded the 7.15am start.
