Competitors in an adventure race in the Coromandel, including former All Black Richie McCaw and wife Gemma, are being warned heavy rain may make a tough event even tougher.
The ARC Adventure long course is expected to take teams anywhere from 13.5 hours to 21 hours to complete on Saturday while the short course is expected to take between six and 10 hours.
It is McCaw's second ARC Adventure - with the four-person Price Waterhouse Cooper team headed by Rob Nichol, chief executive of the New Zealand Rugby Players' Association, Wanaka's Sarah Fairmaid and adventure race world titleholder Bob McLaughlin, the Waikato Times reports.
His wife Gemma is competing with friends.
Competitors in the long race have been warned of an extremely tough trek with no shortcuts.
"Many will certainly be going into the night and they'll need to be prepared to bivvy down in case things don't go to plan or they are forced to stop for a river to go down," says race director Andy Reid.
Last weekend two 17-year-olds died in the Waitakere Ranges when a heavy downpour caused a river to rise quickly, prompting safety warnings about river crossings.
ARC Adventure competitors were reminded at a briefing in Pauanui on Friday night that they needed to carry the appropriate gear and plenty of food.
They were told gear had to be cleaned thoroughly to protect against the spread of Kauri dieback disease in the dense forest that competitors will traverse in the course of the race.
Races feature elements of hill, bush and river running, trekking, mountain biking, navigation and rifle shooting, rope work and some mystery activities.