Three foreign tourists had to be rescued from the Tongariro Crossing, one of whom was found trying to cut steps out of the ice with a rock.
Police say the three weren't fully prepared for the conditions.
Around 11am on Friday, police were called by a Slovenian couple in their mid-20s who'd slipped and fell - but were uninjured - on ice near the North Crater.
They'd started the alpine crossing from the Ketetahi Hut, and had made it past the Blue Lake, but when they couldn't get any further than the Emerald Lakes, phoned police.
Taupo Senior Constable Barry Shepherd says while the couple had adequate clothing, they didn't have the right equipment to deal with the ice, such as crampons and an ice axe.
The Greenlea Rescue Helicopter was sent to the scene with a paramedic and Land Search and Rescue on board, but low cloud meant it couldn't reach the couple.
Police then asked two Department of Conservation staffers based at Mt Ruapehu to head to the area on foot along with Search and Rescue.
They couple was found safe and they group began the walk out to Oturere Hut, where they found the third tourist - a Chinese national.
They stumbled across the man, in his late 20s, trying to carve out steps to climb Oturere Valley using rocks.
The trio's saviours got them to the valley where they were eventually picked up by helicopter and flown to Mangatepopo Rd.
Snr Const Shepherd says it was lucky none of them were injured or needed medical attention.
He called on locals to give visitors good advice before they head off, saying the tourists may not fully understand the changeable weather.
"The conditions can change rapidly and while you start out with sunshine and clear skies, if the cloud comes over the snow can freeze making conditions very slippery without proper equipment."
Trampers are putting their lives at risk by not being fully prepared, Snr Const Shepherd says.
"The mountain was very busy today with lots of people under the supervision of guided tours who know the area well and do a great job.
"I would encourage more people, especially visitors to the area, to seek advice from these people before attempting the crossing alone," he says.