An effort to help raise funds for the Orokonui ecosanctuary, the challenge includes race and walk components.
While the walk was last weekend, the race was the key feature of the event and reached its limit of entrants earlier this week.
"We’ve been full for a little while," race director Chris Baillie said.
"We capped it at 100 this year because its our first year and we wanted to make sure it all went well before we went big."
It had attracted an even split of men and women, with plenty of masters and veterans runners in the over-35 and over-50 grades as well.
The run followed an 18.5km track around the area of the sanctuary, covering various terrain.
Baillie expected the toughest section to be a steep climb from sea level to 300m above at the 15km point.
She said the top runners would likely complete the track in about one-and-a-half hours, while the slower runners would finish in three hours.
The organisation of the event had gone smoothly, although Baillie expected next year’s to be far easier having learnt a lot from this year’s experience.
A big team of volunteers from the sanctuary had stepped up and would help with various jobs on the day.
Last weekend’s walk attracted 156 entrants.
They had the option of walking or running around an 11km course through the sanctuary.