Whanganui's Elly Arnst in all-conquering Revenant Ultra Adventure Run in Southland

Elly Arnst and Matt Bailey wait to begin the Revenant Ultra Adventure Run. Photo / Supplied

It was something they knew they were bound to fail - but Whanganui's Elly Arnst and her partner Matt Bailey came away from the Revenant Ultra Adventure Run feeling great.

The Revenant is an extreme adventure run that started at Welcome Rock in Southland on January 13. The 24 competitors aimed to run 190km over steep terrain, with 1600m of climbing, during just 60 hours.

It must be done without digital navigation aids and only four people - all male - have finished it since its first year in 2019. Finishing is winning.

This year nobody finished, Arnst said. Nobody even reached the fourth lap.

Arnst had hoped to be the first woman to finish, but wasn't disheartened because even the really experienced people couldn't make it.

"Everyone said it was really hard."

The run started around 9pm and there wasn't much time to look at maps and check routes. It got dark fast and Arnst didn't know the area.

"I think the hardest thing was choosing routes in the dark. Without any local knowledge you don't know the shortcuts," she said.

Competitors have 30 hours to do the first two laps. Arnst and Bailey did the first one, with 14 checkpoints, in 17-and-a-half hours. They started the second one, did two checkpoints and realised they wouldn't finish in time and would be eliminated.

"We decided to backtrack and walk out the shorter way and not do another night of sleep deprivation."

Competitors officially leave the run by tapping a bottle of Welcome Rock whiskey. Photo / Supplied

Arnst's friend and fellow adventurer Katie Wright, formerly of Whanganui, finished the first two laps and didn't start the third. She was in her third year at the Revenant, Arnst said.

Only one person started the third lap but did not finish it.

The course of the run changes each year. Anyone who finishes it in the 60 hours gets a shot of Welcome Rock whiskey.

Arnst felt good about her performance and was fresh enough to go for a run a few days later.

"Physically and mentally it was easy, much easier than the other things I've done," she said.

The Ruahines have been perfect training for her and Bailey, who did a gruelling six days there during the New Year break.

"We never came across terrain [on the Revenant] as hard as that."

The best thing about the run was hanging out with the other competitors and she may attempt the Revenant again, Arnst said.

In April she and Wright hope to make a north to south traverse of the Tararua Range, on a recognised route, and finish within 24 hours. They've already done two traverses on other routes and they could become the first women to complete all three, each within 24 hours.