When the text comes, these volunteers down tools to help strangers in their hour of need. But their numbers are shrinking.

Search and Rescue operations are not for the faint-hearted. We talk to the 'good bastards' who get out of a warm bed on a cold night to go in search of perfect strangers

It took 11 people searching in the dark, dodging streams that had turned to torrents to find a couple who were lost among the alpine cliffs of Mt Ruapehu last week.

Wet and exhausted, the two were guided back to safety step by step, by highly skilled volunteers who put their own lives on hold to save two strangers.

The Ruapehu rescue last week was one of hundreds of missions every year involving LandSAR groups.

Every operation is different, but many have the same scenarios - the lost or missing were underdressed, exhausted, without food and shelter, and without emergency locator beacons.

Wanaka Search and Rescue volunteer Roy Bailey says members do the daring - sometimes dangerous - work for free because they want to help others.

"We're trying not to put our lives on the line," he says. "We're trying to save other lives but quite often you're putting your life on hold to go and do it.

"Pretty much you're there to help strangers in their hour of need really, which is pretty cool."

Bailey, who is the canyon swiftwater team coordinator at Wanaka among other roles, says many people put in hundreds of unpaid hours but they are well trained in search and rescue.

He tells The Detail about a rescue he was part of where a young adventurer was stuck on a bluff in Mt Aspiring National Park, 24 hours overdue from his trip. Without a locator beacon to pinpoint the man, the rescuers had to narrow the search in a massive area, helped by the helicopter which picked up boot prints in the snow. But searchers on the ground lost his trail and it was only through their special tracking skills that they eventually found him several hours later.

"For me I guess it was memorable because it was all over our training. We managed to track the guy up the Young (River), over the (Gillespie) River Pass and part way through the Siberia Valley on the other side.

"We actually managed to find this guy who was totally bluffed-out and stuck."

A tragic memory that Bailey lives with is the recovery of the body of his young friend Jeremy Norbury who drowned while kayaking with a group on the Turnbull River, South Westland, last February.

"It was a dangerous, steep whitewater section that he was stuck in, and you do all you can to minimise the risk and that's what we train in ... looking after ourselves, trying to make things as safe as possible."…

Go to this episode on rnz.co.nz for more details