Tourist numbers in New Zealand are reaching a "tipping point", spoiling Kiwis' experience of the great outdoors, say climbing and tramping groups.
They say many New Zealanders choose to avoid the Department of Conservation's (DOC) nine Great Walks and are becoming increasingly upset at the number of people on secondary trails.
Almost 120,000 people visited the Great Walks in the 2015/2016 season - an increase of 12.4 percent over the previous year.
Sixty percent of those were international visitors and on some tracks, such as the Kepler and Routeburn, Kiwis made up only about 25 percent of walkers.
In 2011/2012, the only other season where figures are available for all of the Great Walks, there were about 80,000 visitors in total, 50 percent fewer than in 2015/2016.
Federated Mountain Clubs president Peter Wilson said many New Zealander trampers opted for less well-known walks, but were becoming increasingly frustrated to also find them busy.
"Ultimately New Zealand is three shaky islands and there's only a limited number of places that Kiwis can go. We have to bear in mind, as we are pushing up tourism numbers, if we don't manage it right, they'll be a flow-on effect of disillusioned Kiwi trampers who do want a quiet space in the hills."
Mr Wilson said he was not sure if DOC had a strategy for dealing with the demand.
"You can't just keep growing tourism numbers, there will be a tipping point and we're probably at that tipping point in some areas at the moment.
"The Tongariro Crossing, the Eglinton Valley at the height of summer in Fiordland, and if we don't have a plan for tourism - and at the moment we don't have a plan for tourism - we'll see more of it. We'll see more Kiwis who feel pushed out of their own backcountry."
Otago Mountaineering and Tramping Club president Richard Forbes said he had noticed the number of people in the backcountry increasing.
"Places like in the Tukituki are getting quite crowded particularly in the summer time. And also the Rees and the Dart Track and I believe the Greenstone and Caples Tracks too.
"And I know DOC is keeping pretty close eye on it and thinking of perhaps having booking systems for some of the huts on those tracks as well."
Mr Forbes said some of the tourists left unpleasant surprises for club members.
"You know we do get a bit upset when we find people have been doing their business in the bushes and not burying their waste and leaving rubbish around.
"I guess some tourists are doing things on the cheap a bit and avoiding the Great Walks and going into these other areas, but not doing it correctly. So I guess there needs to be a bit of education going on here."
Mr Forbes was also concerned that the tourists' lack of outdoor skills could lead to more accidents on out-of-the-way tracks.
DOC recreation manager Richard Davies said he was thrilled more people, including more Kiwis, were using its facilities.
He said the record number of people using the Great Walks was something to celebrate, not fear.
"From our perspective people going out and walking these tracks or paddling down these rivers or climbing these mountains etc. That is our business to get people out enjoying it and so for us it is a success."
Mr Davies said there was still capacity to grow numbers on the Great Walks, but the fact people were visiting secondary tracks was a sign DOC's strategy to spread the load was working.
He said in the past perhaps New Zealanders had been spoilt and were able to have 20-bunk huts all to themselves, but that was not a good business model.
True wilderness experiences were still there for those who want them, Mr Davies said.
"Most of our places are very little used. We've got an extensive backcountry network where you will be able to plan a trip and see no one so I still think there is a lot of opportunities to have whatever kind of experience they want."
Anyone hoping to tackle one of the Great Walks over the holiday period, however, could forget Milford and might want to consider taking a tent elsewhere, as most huts are booked out until mid-February.