Remarkables Ski Area manager Ross Lawrence said three snowboarders hiked outside the skifield's boundary into an uncontrolled, unmaintained area beyond Lake Alta.
This was despite warnings issued on Friday to skiers and snowboarders at Queenstown and Wanaka skifields to stay within the boundaries because of the high risk of avalanches in back-country areas.
A large avalanche in the Southern Alps' Ragged Range on Friday afternoon killed Australian heliskier Llynden Riethmuller (61) and buried Melbourne multimillionaire real-estate trader John Castran (53) and his son Angus (23) for 10 to 15 minutes, before they were rescued by their mountain guides.
Mr Lawrence said that in the case of the Remarkables incident, the snowboarders rode the Shadow Basin chairlift then hiked on to a ridge, 200m past the Elevator, Escalator and Alta chutes.
The Queenstown snowboarder, watched by his two companions, rode down the area, triggering an avalanche of unstable snow pack.
It was rated at level 3.5 out of 5 and was certainly big enough to bury houses, Mr Lawrence said.
"He was lucky. If he had got trapped in the avalanche, he would have been pushed into the lake and been buried," he said.
It highlighted the risk of avalanches, and skiers and snowboarders should heed the warnings, he said.
The snowboarder, who declined to be named, said it was "scary stuff".
"It was pretty big following behind me, but I was well ahead of it though," he said.
He rode down to the lake and saw the avalanche surging into the frozen lake.
The three snowboarders had been to the area many times before but now realised they should have asked ski patrol's advice before venturing into back-country.
The experience would not put him off from back-country boarding, but he would always first check for avalanche warnings.
The Mountain Safety Council has warned skiers, snowboarders, climbers and trampers to avoid back-country travel until further notice.
The council's back-country avalanche advisory shows danger still high for Wanaka and Queenstown back-country areas.
Several significant avalanches had been reported over the weekend in Wanaka.
New snow in Wanaka in the past week sitting on a pack with buried weaknesses, combined with gale force winds, has created widespread instability.
