The course sees racers first run 2.2km before a 55km cycle. Once off the bike, the competitors journey over a 30.5km mountain run, climbing more than 1km upwards along the way.
After that is a 15km cycle and a 1.3km run before arguably the toughest part of the course - a 70km kayak down the Waimakariri River.
A gruelling 69km cycle is the finale, but Cole-Baker said the kayak was definitely the toughest part.
"The toughest hours were spent in the kayak. I was in a lot of pain for the last 20k," he said.
"Was great to get back on the bike for the final 70km and move up through the field, but I had lost a lot of time by then.
"I over-cooked myself in the first 20 minutes in the darkness trying to bridge a 15-second gap to the leaders which cost me later in the day."
Defending champion Sam Clark took out the title in 11:02:43secs to beat three-time champion Braden Currie, who held a 12-minute lead going into the kayak leg.
Cole-Baker said he had a great time out at the event, but was unsure whether he would return for the 2018 edition.
"It's fair to say that it was a big day out. I was very happy to get to the east side, it's a true test across some amazing terrain," he said.
"I would love to come back, although will be tough as it is a big haul from Northland, especially as more specific training on the course would be needed and that's a big expense and time away from family.
"But going forward I am excited to hit the local events in the next few weeks, the Kai Iwi triathlon and the Wild Kiwi event."
