A NSW man missing on a multi-day hike in "challenging" Tasmanian wilderness is believed to be without a personal locator beacon.
Ground crews were deployed to the Eastern Arthur Range on Tuesday afternoon after the 27-year-old failed to finish a traverse track as expected.
He set off from a campground on July 16 and told friends he was planning to complete the walk on Saturday or Sunday.
A rescue helicopter began searching on Tuesday morning, before four police, two wilderness paramedics and four SES volunteers joined the effort.
Tasmania Police were notified around 4pm on Monday after a friend reported the man was overdue and hadn't been in touch since Friday.
"The Eastern Arthur Range Traverse is challenging and would take most experienced bushwalkers six to nine days to complete," police search controller Ben Cunningham said.
"While he is reported to be an experienced bushwalker, we don't believe the man is in possession of a personal locator beacon."
The 72km hike, in Tasmania's southwest, is described as being for physically capable and highly experienced walkers who are confident with navigation, cliff and rock scrambling and extreme weather.
