NEW ZEALAND’S chief conservation officer, Lou Sanson, caused a stir in October by suggesting that it might be time to start charging tourists for using the country’s wilderness trails. New Zealanders are keen fans of their national parks. Many would be outraged at having to pay. But many also worry about a huge influx of foreigners who have been seeking the same delights.

In 2016 New Zealand hosted 3.5m tourists from overseas; by 2022 more than 4.5m are expected every year—about the same as the country’s resident population. Tourism has overtaken dairy produce as the biggest export, helped by a surge in the number of visitors from China. The national parks, which make up about one-third of the territory, are a huge draw. About half of the foreign tourists visit one. They are keen to experience the natural beauty promised by the country’s “100% Pure New Zealand” advertising campaign (and shown off in the film adaptations of “The Lord of the Rings” and “The Hobbit”, which were shot in New Zealand’s breathtaking wilderness).

But for every happy Chinese couple snuggling up for a selfie next to a tuatara there is a grumpy New Zealander who remembers the way things used to be—when you could walk the tracks without running into crowds at every clearing. Many locals now wonder why their taxes, as they see it, are paying for someone else’s holiday. Mr Sanson would seem to agree. Entry fees could be used to upgrade facilities such as cabins, car parks and trails. A varying levy could also help reduce numbers at some of the popular locations by making it cheaper to use lesser-known, but no less beautiful, trails farther afield.

Some are not so sure it would work. Hugh Logan, a former chief of conservation for the government who now runs a mountaineering club, worries it would cost too much to employ staff to take money from hikers at entrances. It would also be difficult to prevent tourists from sneaking around the toll booths.

Some argue that it would be easier to charge visitors a “conservation tax” when they enter the country. The Green Party, the third-largest in parliament, says that adding around NZ$18 ($12.50) to existing border taxes would still make the total amount levied less than visitors to arch-rival Australia have to pay. But some travel companies oppose the idea. They note that tourists already contribute around NZ$1.1bn through the country’s 15% sales tax. Better, such firms say, to use foreign tourists’ contribution to this tax for the maintenance of the parks.

Among the fiercest critics of a charge are those who point out that unfettered access to wilderness areas is an important principle for New Zealanders. It is enshrined in a National Parks Act which inspires almost constitution-like devotion among the country’s nature-lovers. Mr Sanson has a rocky path ahead.