A Dunedin doctor and his brother-in-law are attempting the first unsupported crossing of Antarctica.
Richard Stephenson, 40, and his brother-in-law Gareth Andrews will begin the 2600km journey with little more than a sled and some skis.
They are expecting it to take about 110 days and will start in November next year.
The pair will begin at the edge of the ice shelf and make their way across the continent, to the other ice shelf, by skiing while dragging their supplies in a sled.
Stephenson told the Herald the feat is right at the edge of what is humanly possible.
"There's good reason this hasn't been done before. It's a huge physiological and logistical endurance challenge, just to see if we can do it really."
The emergency physician, born in England, lives in Dunedin with his family including his 8-year-old son Will and 6-year-old daughter Rose.
He has been a keen mountaineer and tramper for as long as he can remember.
The idea for the expedition across Antarctica started during a different trip.
"Gareth had this idea to ski to the magnetic North Pole and was looking for someone to go with him.
"I overheard him talking to my sister about it and thought it sounded like a great idea so not knowing Gareth that well at that point, I decided to tag along."
Thus began a partnership that pleasantly surprised both of them.
"Essentially we realised over the course of that trip, a 600km ski across the frozen Arctic Ocean, that we get on well as a pair and have complementary skillsets.
"That started off our history of expeditioning together."
Since then they have completed numerous trips and endurance challenges including the first unsupported ski and raft crossing of Iceland.
"On a trip like this to Antarctica, you're essentially living in a small tent together for the best part of three months and how you get on with your partner is key, probably the single most important part of the expedition."
Planning for the trip is all about attention to detail and optimising every single component, he said.
Training consists of two main elements, strength and bulking as well as the fitness.
"We'll be pulling sleds weighing between 180-200kg which is pretty hard work.
"You need to start off as strong as possible whilst maintaining the level of aerobic fitness required to cover 23km a day."
He said it's inevitable they will lose significant amounts of weight so they need to anticipate that and build a strong aerobic base.
"Really pulling a tyre along a beach is the closest way to replicate the activity of pulling a sled. So there's essentially been many, many hours of doing that."
That runs parallel to a rigorous nutrition programme where all aspects of their diets before and during the expedition are carefully analysed.
"That's so we are eating the right things to allow us to train as optimally as possible."
The challenge of crossing Antarctica unguided has been riddled with controversy as many have attempted it over the years.
In 2018, 33-year-old Colin O'Brady reportedly completed the feat but leaders in the adventure and polar communities did not agree with his claims.
They cited the route he took meant he did not technically cross the continent.
Many others have attempted to cross but suffered the same fate with holes being found in their claims meaning the accomplishment is still up for grabs.
To mitigate the confusion, the Polar Expeditions Classification Scheme (PECS) was developed using standardised keywords and definitions which helps to categorise people's journeys.
"We have huge respect and acknowledgment of those who have gone before us and done things in Antarctica.
"Some of the controversies, it's a shame that they detract from what are truly impressive feats in their own rights."
Stephenson said he is feeling incredibly excited.
"It's a mix of excitement and being pretty daunted as well. We are going into this with our eyes open.
"We know it is a significant challenge. The biggest thing is the opportunity to spend time in an amazing wilderness environment."