Experienced hiker Hadi Nazari, 23, was last seen on Boxing Day descending the challenging Hannels Spur trail in NSW's Kosciuszko National Park.
A large-scale search involving NSW Police, the State Emergency Service, National Parks and Wildlife Service, NSW Ambulance, and volunteers when Mr Nazari failed to meet friends at Geehi campground.
Experienced hiker Hadi Nazari, 23, was last seen on Boxing Day in NSW's Kosciuszko National Park. (HANDOUT/NSW POLICE)
Rubbish and hiking poles believed to be his were found near the Kosciuszko River on Tuesday, narrowing the search.
Tour company Snowy Mountains Back Country lead guide Doug Chatten told AAP the Hannels Spur track, despite its elevation change, was not so steep that it required "hand-and-foot climbing".
"It's easier walking up, because you're controlling your weight - when you're walking down … it's just hard work," he told AAP.
The festive season is a busy time in the mountains.
"There's quite a few people walking that track, but it's not like it's continuous, Everest-style, back-to-back … it does get used a bit," Mr Chatten told AAP.
Searchers include police, the SES, national parks and wildlife and ambulance staff and volunteers. (Supplied by Nsw Police/AAP PHOTOS)
But things can quickly become much more difficult for anyone off the track.
"If you're off the track, it's bloody tough country," Mr Chatten said.
"It's no easy walk, that's for sure … if you're off the track and you can't find your way back and you're moving around, you'd be a hard person to find."
While the longer days offer more light, the summer poses other hazards.
"It's tough and long, hot, dry days and we're going through a very hot, dry period at the moment," Mr Chatten said.
The terrain is so dense searchers in some parts of the park can't see their feet, police say. (Supplied by Nsw Police/AAP PHOTOS)
Acting Superintendent Jill Gibson said specialist teams with winching capabilities and aircraft were aiding the search but rugged terrain and dense vegetation make it challenging.
"The bushland is so dense that searchers in some parts can't see their feet," Ms Gibson told reporters on Friday afternoon.
She said police were still hopeful of finding Mr Nazari.
"We are continuing to search for Hadi. We are not giving up hope of finding him alive," she said.
The Hannels Spur trail, with its 1800m elevation change, is one of Australia's most difficult bushwalking routes.
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