Searchers have so far failed to find two trampers missing in Kahurangi National Park, but an experienced rescue volunteer says there could still be a chance for the pair.
Jessica O'Connor and Dion Reynolds, both 23 and from the Tasman area, started out on 9 May. They are understood to have entered at the Anatori River car park, in a remote part of western Golden Bay.
Police started searching on Tuesday and a drone with infrared capability was flown last night. Police said it would be used again in today's land search.
Sherp Tucker, who has worked in search and rescue since the 1960s - though is not involved in this search - said the area was full of bluffs and dense vegetation.
Even though the terrain they were thought to be in was rugged and difficult there was still a chance for the pair, he said.
"This is a true wilderness area and the restriction on travel is mainly because of the vegetation, but if these people have outdoor skills and fitness on their side and they've taken the right kind of gear, there's no reason they aren't still alive."
Tasman Police Senior Constable David Cogger said yesterday they had found very few clues but believed the trampers were well prepared.
More teams had arrived to search a wider area of interest while others have now been sent to search an area north of the wider search area.
Tucker described the area as a "rugged wilderness" with few tracks that were actually walkable or which allowed people to travel quickly.
"I've walked the area a couple of times, if you can call it that - it's quite a scramble. It faces the west and catches all the westerly air flow and the vegetation is very compact in there.
"The first time I went from Westhaven to Karamea was meant to be a three-day trip but it ended up being a six-day trip simply because of how tight the vegetation and scrub was. It's at times not all that high, but it's very thick."
Tucker said the trampers were perhaps lucky there had not been much rain in recent weeks.
He said the hike immediately from the car park from where the pair was thought to have left was "away from civilisation".
"Like everything there in that area of north-west Nelson away from the coast, you're straight into natural wilderness. You have to be content to travel off-track because there are none. It's exploration in its truest sense."
Tucker said there were steep inclines in and out of creeks, which also posed challenges for rescuers.
He said the small number of people who ventured in there could also be an advantage, especially if any signs were found.
"The sign you do find is quite often significant if you don't think anyone else has been there before."
Tucker said the mistake the pair seemed to have made was not fully explaining their intentions to anyone.
"You can always tell a mate where you plan to head."