Richie McCaw has set off on a gruelling seven-day, 530km expedition race to raise money for cancer charity Cure Kids.
The former All Blacks captain and three teammates are taking on 60 other teams in the 2016 GODZone race, which started at Kaiteriteri beach in Tasman at midday.
The teams will traverse three national parks during the race and go white water canoeing on the Matakitaki River, complete a 52km trek over the Red Hills in the Richmond Range, and summit Mt Owen in Kahurangi National Park.
It will be McCaw's first expedition race, while his teammates - Rob Nichol, Sarah Fairmaid and Ben Meyer - have plenty of experience between them.
McCaw posted a photo of the team to Facebook last night, saying: "Got all our gear ready. Can't wait for the start tomorrow on our big adventure."
The post included a photo of the team's gear and food, which was neatly packed up in water-tight bags.
McCaw spoke about the challenge ahead of today's race.
"We know we are in for one heck of a challenge that will push us all to the limits mentally and physically," he said.
"I know we definitely won't be lacking for motivation by supporting such a great cause like Cure Kids but it is definitely going to be a true test of our grit, determination and resilience."
Nichol and Meyer took part in the race for Cure Kids last year, along with former All Black Ian Jones and experienced adventure racer Sia Svendsen.
"It was an amazing experience that produced a great result for Cure Kids and the team," Nichol said.
"This year we are thrilled to have Richie and Sarah on board to take on this challenge and support what is a fantastic charity in Cure Kids."
GODZone race director Warren Bates, who designed the course, said the teams only received their course maps and booklets at 6am today, which "broke the veil of secrecy".
"It's an important part of the ritual of adventure racing where navigation plays a huge part of a team's race strategy," he said.
"Not knowing where the course goes prior to race start, stops teams from doing too much pre-planning and recces. We take racers into unique locations where most people will not have been before and so it becomes a navigational exercise that they have to cope with on the move."
The nine-stage race starts with coasteering off Kaiteriteri Beach followed by a 4-6hr kayak up the coastline to Rabbit Island, where teams will complete a short orienteering course before mountain biking through to the Richmond Ranges.
Bates said the first teams were expected to arrive at the Wairoa Gorge transition site around 11.30pm today.
From there they would head into the first major trek of the event, a 52km climb over the Red Hills and down towards Tophouse and St Arnaud.
They would then get on their bikes to ride to Lake Rotoiti in Nelson Lakes to undertake an orienteering course set up and designed by the Nelson Orienteering Club. Once completed they would ride to Lake Rotoroa and paddle white water canoes up to the head of the lake.
The teams would leave the boats there and head into the second course trek over the Mole Tops and down to the Matakitaki River. Then it would be an exciting 50km white water paddle through rapids down to Murchison.
Teams would then trek 35km through the Kahurangi National Park to the summit of Mt Owen before heading on a 140km mountain bike ride towards Totaranui and the last leg of the race.
"Paddling down the Able Tasman National Park from Totaranui to the finish line at Kaiteriteri Beach is going to be an epic way to finish the event," Bates said.
As well as the 61 teams taking part in the full course, 10 teams will start tomorrow on a shorter course.
• To support Team Cure Kids for GODZone, text GODZone to 933 to donate $3 to the charity.
