Samantha Hayes didn't make it to the top of Mt Aconcagua, having to turn back "as the altitude and cold got the better" of her - less than 300m below the summit.
The Newshub Live at 6pm presenter and mountain climber took to Instagram to recount the "extraordinary day", in which she battled -30degC and ended up oxygen-deprived and hyperventilating.
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Hayes posted a photo taken of her high in the Andes Mountains in Argentina together with the emotional message.
"Well, I didn't make it to the 6962m summit of Mt Aconcagua and I'm still coming to terms with that, but I did get to 6700m before the altitude and cold got the better of me," she said.
"I saw members of my group with the first stages of frostbite on their faces and hands and a determination to get up the mountain which was breath-taking. In the end, I was shaking and spent, breathing so hard I was hyperventilating."
The 2018 Dancing With the Stars NZ winner says turning back was "a horrible decision to make", but she knew she needed to use her remaining energy to get down the mountain safely.
"The night before our guide checked my oxygen saturation at 6000m and it was between 55-67. In hospital, they put you on oxygen if it's below 95! I just wasn't getting enough air to keep going," Hayes said.
"My legs are jelly but my heart is full. It feels great to have attempted a challenge like this, even if the mountain won."
She also said that of the 60 people attempting to summit, fewer than ten made it.
Hayes will return to her role on Newshub Live at 6pm alongside Mike McRoberts later this year.