Two young, ill-equipped foreign trampers would be dead if it wasn't for a heroic night-time rescue mission, say police.
The Irish woman and Latvian man, aged in their 20s, got into trouble late on Saturday afternoon in freezing conditions in Nelson Lakes National Park.
A three-strong LandSAR rescue team, including a doctor, tramped for nine hours through the night battling snow, high winds and a wind chill of -18C to reach the stricken pair early on Sunday.
They were found to be suffering from severe hypothermia and unable to help themselves. The rescuers worked to raise their body temperatures before a break in the weather allowed a helicopter to fly them to safety.
"The reality is that without these people we may not have been able to reach these two young foreign travellers in time to save their lives," Inspector Mat Arnold-Kelly said.
"Given their condition when they were found it is unlikely they would have survived very much longer unassisted," he said.
"These rescue teams are volunteers who gave up their own time and were prepared to put themselves in a difficult and uncomfortable position for the sake of complete strangers who had made poor decisions."
Insp Arnold-Kelly said the rescued pair had inadequate equipment, clothing or experience for the tramp they undertook.