Queenstown businessman and adventurer Erik Bradshaw initially thought being first to ski the length of the Southern Alps "a crazy idea".
However, on October 26, Mr Bradshaw (43) completed the 800km journey, which was the vertical metre-equivalent of climbing Mt Everest six times. He had skied along the spine of the South Island.
Beginning his journey on August 8 from St Arnaud (Nelson Lakes), Mr Bradshaw completed his feat in Fiordland. It was the first time the Southern Alps had been traversed on skis and just the second winter traverse, with Graeme Dingle and Jill Tremain completing the first winter traverse 30 years ago, in 1971.
To succeed, Mr Bradshaw had to invent ski equipment, including an exoskeleton binding of carbon fibre and titanium which fitted over a normal walking boot to transform it into a ski boot with crampons.
He also needed a personal plan to cope with extreme winter conditions in the Alps.
"Without doubt it is the hardest thing I have ever done. I had to know what would work and what was too dangerous. If I was too timid I would never succeed, but if I was too bold I wouldn't make it home again.
"Developing a good understanding of how my body worked was critical as I pushed myself very hard for 12 hours per day, skiing and climbing then camping in sub-zero temperatures, waking the next day and repeating day after day. To do that without getting tired, sick or injured required a careful and innovative approach."
The traverse was completed in several legs, with Mr Bradshaw restocking and repairing equipment when his journey brought him into contact with civilisation.
At one point he broke a pair of expensive European skis and had to make a replacement pair with the help of friend Richard Harcourt during a supply stop.
He also had to endure raging storms in a tiny tent, an experience he said was sometimes "miserable".
"But other times it was breathtakingly beautiful, with towering snow-capped mountains, blue skies and amazing snow.
"When I first thought of attempting this ski traverse, I thought it was a crazy idea, but as I developed new ski equipment and experimented with how to travel fast in the mountains I realised I could succeed, with great preparation and focus.
"In the end, the hardest part was maintaining the optimism and mental drive to keep pushing over what is a huge chain of steep mountains."
One of the highlights was visiting remote areas; for example the Te Naihi Rivers, a place that had "probably never been visited on skis before".
Mr Bradshaw started backcountry skiing when he was 15 and has been a keen mountain climber since he could walk.
He has climbed and skied throughout New Zealand and the world, including the Antarctic.
In 2006, along with partner Christine Ryan, he was awarded a Royal Humane Society Bravery medal for the rescue of trampers in the Matukituki.
He and Ms Ryan, who live in Queenstown with their 15-month-old son, run tourism-specific software business Ibis Technology.