With his vision impaired, no food and little clothing, he spent the next three nights in an area the size of a family car in freezing conditions, with little to keep him going -- except his trusty dog, Whai.
"I've been in some ugly places but never one with no options. The thing was to stay alive and go to my daughter's wedding, but it was a lot of mental torment," he said.
The 48-year-old prison officer had set out on a day trek on Wednesday in Lake Taupo Forest cutting a horse track when he came across a waterfall on the Waitotara Stream and tried to climb down "Bear Grylls style".
He fell, knocking himself out and later awoke to find himself overlooking a 50m drop to the stream below, butted against a series of bluffs that were too steep to climb out.
He had lost his GPS system, torch and balaclava while descending. He also lost his glasses so he could barely see.
"Everything was blurring and the danger was I could have stumbled or slipped," he said.
"There was no exit left, front or above. It came down to taking cat naps and trying to stay dry but what made it worse was it was wet and frosty."
Mr Severne told his dog Whai, a German shorthaired pointer, to stay on the ledge above him but after a night of howling the dog jumped over the waterfall to be with him.
He put the dog inside his clothing to keep him warm and moved his legs as fast as he could to keep the blood flowing.
He tried to stay awake when the sun went down. "Sleep was out of the question ... and food wasn't an issue because there wasn't any. It was about trying to stay warm."
Despite watching search planes and helicopters pass overhead in vain, he remained hopeful of rescue even though the searchers' yells for him were drowned out by the waterfall.
By Friday dozens of hunters, search and rescue staff, forestry crews and members of his family -- some of whom had come from Australia to help look for him -- were out in force.
Mr Severne, who is also on heart medication, said his hope started to fade shortly before his rescue on Saturday at 1pm.
"That was about the time I got a little bit of light and warmth but it didn't last long and it would go. I was getting down then because I was starting to shake uncontrollably. Then my chest started to go sore and I thought I was going to die."
A friend, Brett Cooper, found him after discovering a disturbed area of bush nearby -- and his bush shirt that he had dropped during his tramp.
Not long after Mr Cooper, whom Mr Severne had helped to save in similar circumstances about 15 years ago, saw Whai on the ledge and his mate's legs sticking out.
Mr Severne spent Saturday night in Taupo Hospital recovering from hypothermia with his daughter at his bedside. Yesterday he was back at home.
Senior Constable Barry Shepherd of Taupo police said searchers never gave up hope of finding Mr Severne alive.
"It's a remarkable survival story but people can do amazing things in that kind of adversity," he said.
- James Ihaka of the New Zealand Herald
