At 8am today, 18 runners embark on a journey of self-discovery as they attempt the ultramarathon distance of 84.7km at the Molesworth Run.
The field size is limited to 20 for the individual run and to 65 teams (two- and four-person) for the run that climbs through the high country of the Marlborough region.
The gruelling track traverses gravel road and climbs up Ward Pass to an elevation of 1145m, before descending into Isolated Flat.
Runners complete a track that spans 250ha of expansive grass and tussock lands, bounded by rolling mountains and huge scree slopes.
"It is pretty unique country to run through on New Zealand's largest working farm," said race organiser Maurice Brown.
"We don't oversell the entries because it is not a commercial venture and we don't want to ruin the experience of running through the high country."
Solo runners must be proven ultradistance competitors and must supply ultra events times with their race entries.
Teams of four will run about 21km each and teams of two about 42km each. Teams of two must run Legs 1 and 2 or Legs 3 and 4 - running alternate legs is not allowed. There is a time limit of 10 hours in place for the run.
The Molesworth Run has been in operation for 17 years and attracts a good crowd who enjoy a soak in the Hanmer thermal spa after the run.
"We see many of the same faces year after year, and many have done it all 17 years," said Brown.
"There is a fantastic community that support this event."
John Thirkettle holds the men's record for the 84km distance with 6hr 32min 14sec in 1996 and Wynnie Wu Cosgrove ran 7hr 32min 56sec for the women's record in 1995.
The run comes with a caution of the effect the altitude can have on the conditions. At about 1000m above sea level, the high country weather patterns are extreme, warns the website.
"Severe heat, little shade and limited water, can be countered with snow and severe frost at any time of the year," it says.