The Spring Challenge North will provide a tough test for almost 500 women as they work their way through the Whanganui countryside.
So far this weekend's event has drawn 481 competitors, split into teams made up of three or four people, who will battle through rafting, trekking and biking elements of the course.
The courses are designed by former Whanganui resident Dan Moore, who is putting his experience to good use having previously competed in the Adventure Racing World Championships, Coast to Coast, and Godzone races.
"I'm stoked to return to Whanganui to design these Spring Challenge courses, as it is a bit of an unknown spot for adventure racing," Moore said.
"There's been events pass through the region, like the Mountains to Sea Multisport Race, but none where competitors have to navigate in teams."
The race features three-hour, six-hour, and nine-hour courses which give entrants different options that match their skill and ability.
However, Moore said although the courses seem short in distance, they're not to be taken lightly.
"The courses are primarily on the Whanganui hill countryside and while the stage distances are not as long compared to previous Spring Challenges, the intricate nature of terrain will make up for this.
"The courses will have a character all of their own and will be like no others we have run in the North Island. This is unique country and involves minimal time in public areas."
Competitors won't know the course until they've registered on Friday night, giving them only one night to mentally prepare for the terrain they'll be facing the next day.
The annual event was started by six-time World Adventure Racing Champion Nathan Fa'aave and his wife Jodie, and has been running for more than a decade in the South Island.
It was first held in the North Island in 2016.
Moore thanked local iwi and the wider community for supporting the race in its inaugural visit to Whanganui.
"We are grateful to the local communities and landowners for their assistance in running the event.
"Also we want to thank volunteers who will be helping on the river and with marshall duties, plus the council's tourism arm, Whanganui and Partners, for their support."
A hangi will be laid near the end of the course to feed hungry competitors once they've crossed the finish line.
Registration takes place on Friday at the War Memorial Centre from 3pm to 5pm followed by an official welcome.
The race is on Saturday with prizegiving and an awards ceremony on Sunday at the War Memorial Centre.