Tramper recovering from hypothermia after Kahurangi National Park rescue

A tramper was rescued in Kahurangi National Park after setting off his personal locator beacon. Photo / Nelson Senior Constable Dave Colville

A South Island tramper was unlikely to have been rescued today if it hadn't been for his personal locator beacon, police said.

A search effort was about to kick off this morning for a man who had gone missing in Kahurangi National Park over the weekend, before police were notified that a personal locator beacon had been set off nearby.

But the man was found in an area of the park that police said they were not planning to search today.

"If he didn't have that beacon, he'd still be sitting there," Nelson Senior Constable Dave Colville told the Herald.

Family of the tramper grew worried after they did not receive a call from him on Saturday afternoon when he was expected to have completed the Boulder Lake Track.

Police discovered he had not stayed the night at the track hut after speaking with another hiker on the track, who said they had spent the night alone in the hut.

"It gave us cause for concern, because he had been out two nights in the open, in -5 or -10 [temperatures]," said Colville.

Land Search and Rescue (LandSAR) at Takaka were planning to deploy two field teams to either end of the track before Colville got a call from the Rescue Co-ordination Centre (RCC) saying they had spotted a beacon going off in the nearby area.

The Nelson Marlborough Rescue Helicopter found the tramper "straight away" near the Boulder River, to the west of Boulder Lakes in the Golden Bay area this morning, duty pilot Euan Stratford told the Herald.

The hiker was found near Boulder Lake (pictured) in Kahurangi National Park. Photo / Nelson Senior Constable Dave Colville

"He had an orange banner which made it easy for us to spot him, which was good."

He was winched on board the aircraft and flown to Nelson Hospital.

Police said he was being treated for hypothermia and they were planning to speak to him later today about what went wrong.

The man's wife has flown to Nelson from Auckland to be with him.

It's a good reminder for trampers to carry the right gear, Colville said.

A party that went missing in the same area several years ago took a week to find their way out, he said.