Search and rescue officials say they had no choice but to abandon the search for a tramper lost in Mt Aspiring National Park since Sunday.
Scott Oliver (known as Brock), 41, of Wellington, was last seen on Sunday at 6.30 pm, when he parted with the rest of his tramping group to find an alternative route back to base camp in the upper reaches of the Wilkin River.
They said he was seeking a short cut but his path would have taken him through a rugged and very dangerous section of gorge.
Wanaka Police Search and Rescue co-ordinator Sergeant Aaron Nicholson said an intensive search operation Monday and yesterday by search and rescue volunteers failed to find any trace of him.
The mission included eight searchers, including four river rescue specialists and a helicopter.
Sergeant Nicholson said they found Mr Oliver's footprints into the gorge, but could find no trace of an exit.
He said as a result there was no option but to accept that the missing man was swept away and drowned, and the matter would be referred to the coroner.
Sergeant Nicholson said the area was very dangerous, with huge boulders and raging water.
He said in the absence of any further clues there is unfortunately little else his team could do.
Land Search and rescue official Philip Melchior said the region contained areas that simply could not be searched.
He said searchers reported that water in the gorge was running so swiftly that even calf-deep it was difficult to stand up in.
"Anyone losing their balance while trying to cross had almost no chance of getting out again once in the gorge," Mr Melchior said.