Mr Farnell was climbing Mt Bounds in Marlborough with friends Colin Griffiths and Murray Chapman on a cold, windy June day in 1985.
He took his pack off at the summit, staked it into the snow with his ice axe and was preparing to take a photo of the next peak along.
"I was ready to get the pinnacle in the viewfinder and a humungous gust came along. When I looked around, the pack was gone," he said.
"There was a steep chute that seemed to go forever and I didn't even think of going after it. Luckily the ice axe was not too far down."
He made his way down the mountain and over the years, the lost pack became a distant memory and was soon forgotten altogether.
Last year, Grovetown man Doug Hislop, president of the Marlborough branch of NZ Deerstalkers Association, was crossing the line of mountains on a goat culling exercise when he spied the top of a pack sticking out.
"I carefully removed it from the gravel with the thought that someone's shoulder blades might still be in it - luckily not."
He searched through the pack for some identification and found "R. Farnell, Blenheim" printed on a pair of leggings.
He cut the name off the leggings and wrapped it around an old emergency kit he also found inside and brought the package out with him.
"I didn't know what he (Mr Hislop) was talking about when he rang up and then suddenly I remembered," Mr Farnell said.
Mr Hislop retrieved the rest of the pack and its contents on a trip to the area this year and it now sits as a memento in Mr Farnell's shed.
The contents of the pack were almost all intact, except for a flask that had fallen out.
His sandwiches were still recognisable and a pair of "brand new", woollen socks could still be worn today.
"He is a really nice guy and I appreciated that he had taken the time to bring out the pack."
The lost pack was covered by insurance and Mr Farnell has given the replacement pack to Mr Hislop as he no longer needs it.
The trip up Mt Bounds (2000m) was one of many the trio completed in the eighties.
