Geoff Cumming finds he has plenty of time to think on one of New Zealand's Great Walks.

The thing about hiking," says Wendy, an English tourist, "is that it solves problems you never knew you had."

She explains: "Things you didn't even know you were thinking about."

I say that there's nothing on my mind and I hope to keep it that way.

We are heading up Queen Charlotte Track at the start of an escorted hike with Adventure South, a company that introduces tourists to the scenery and wildlife in our national parks.


We'll greet Germans, Israelis, Norwegians, North Americans, Brits, Irish and Australians, but very few New Zealanders. Some say that's because hardy New Zealanders prefer the tracks where the tourists don't go, but our guide worries that hardy New Zealanders are a threatened species.

I'm one New Zealander who had put even our easily-travelled Great Walks in the too-hard basket, let alone the more remote tracks in our three million hectares of national parks. A childhood folly in the Waitakeres had persuaded me that lugging your accommodation, food, cooking gear and water up and down steep hills for days in this wet climate was not all it was cracked up to be. I was wrong.

These days tour firms do the hard work for you - getting your gear and transport to the other end while you enjoy the scenery carrying just enough for lunch, and the inevitable downpour. They'll even whisk our six-strong group back to a motel, in a town with a pub, most nights. But it's no stroll in the park — we'll cover enough ground to feel we've earned the comfortable bed, hot showers and restaurant dinners.

Our itinerary will expose us to a variety of terrain over five days: the peaceful, bush-lined inlets of the Marlborough Sounds; the granite coast and golden beaches of Abel Tasman National Park; the alpine tussock and mountain ranges above Lake Rotoiti in Nelson.

We're lucky to have as our guide Nick Groves, an English-born Himalayas veteran who arrived here in the 1980s and has since explored every crevice of our wilderness, picking up an enviable knowledge of fauna and flora along the way. He will keep us amused with tales of his misadventures and his default subject: "the secret sex life of ferns".

The first walk eases my lingering doubts about the pleasures of bushwalking — beginning with a bracing water taxi ride across Queen Charlotte Sound to Portage, from where we'll walk 23km back to Anakiwa.

It's a 400m climb to the ridgeline but we're soon enjoying the song of bellbirds and great views of the sounds on a cloudless day. The rhythm of our progress is interrupted only to peer at a tree, where Groves has spotted a well-camouflaged green gecko, or to taste "honeydew"(actually aphid excreta) on the bark of tall beech trees.

Yet it doesn't take long before problems begin to nag. Not far up the track a sign warns that, to go any further, you should have your $12 track pass. It's DoC's way of sharing the cost of maintaining high-use tracks but the trend concerns Groves. How much, if anything, should we pay to walk in taxpayer-funded bush and stay in DoC huts? Groves has seen DoC's capacity to look after the bush — keep predators and weeds at bay and maintain tracks —diminished over the years and this year the Government has again cut its funding.

Some of his favourite tracks have become unusable — damaged in storms and floods or over-run with weeds — and won't be restored anytime soon. At the same time, the Government is throwing millions more into promoting New Zealand to overseas visitors — using postcard images of our parks and coastline.

"John Key doesn't care. He goes to Hawaii for his holidays; he doesn't come here. He sees [conservation land] as an economic unit which needs to make money."

We walk on. Views from the ridgelines of Kenepuru and Queen Charlotte sounds make it obvious why so many foreigners are drawn to these popular tramping routes. Native bush cloaks each peninsula, reflected in the glassy inlets. Baches and holiday homes are tucked discreetly into the bays. A dusting of snow on the Kaikoura ranges completes the picture.

We stop for a snack on a saddle and Groves looks up.

"There's a whole gigantic ecosystem growing on this tree."

He's pointing to a fallen rata, with ferns, mosses and vines shooting off it in all directions.

"There must be 30 species of plant growing on it."

But the issues of access and upkeep of this amazing wilderness will prove a recurring theme over the five days.

On Abel Tasman, one of the better-funded tracks, Groves spots an invasive Australian shrub which has a firm foothold on a coastal corner. Evidence of rodents and possums is never far away.

Is user pays the solution? DoC has already ratcheted up charges to stay in upgraded huts which are "more like hotels"on popular tracks such as Routeburn and Milford. With fewer New Zealanders going into the bush, Groves fears charges could accelerate the decline.

A group of purposeful Germans march past, offering a cursory glance.

"They're having the time of their lives," says Groves.

"This place is paradise on a world scale. But the Government doesn't recognise its potential."

Certainly, a couple in our party think the tourists are getting a free ride in a world-leading attraction. And backpackers don't have a great reputation for paying.

They suggest foreigners should have to buy a licence to visit national parks. Groves agrees a small "green tax" at the airport might help. But how would we police it — there are hundreds of tracks and huts and fewer DoC rangers.

Our final tramp is into alpine terrain in Nelson Lakes National Park. The zig-zag track to the top of Mt Robert, at 1400m, offers contrasting views: heart-shaped Lake Rotoiti and the Wairau valley on one fork; the green-fringed Buller River flowing towards dense, dark Kahurangi National Park on the other. Up close, mountain and silver beech have replaced the red and black beech of the lowlands. Above the treeline, among the alpine grasses are gentians and orchids.

DoC has invested heavily here, creating a "mainland island" teeming with bellbirds, tuis, fantails and white-eyes. Volunteers from Nelson and Blenheim help out on weekends, trapping stoats and rats and tackling the German wasp population. The Honeydew Track, a short loop on the west of the lake, is an educational walk with signs explaining the forest and wildlife and the pests and weeds that threaten them.

As Groves points out, it's fine to enlist volunteers near population centres — but who will take care of the rest? He believes the answer lies in much more funding for DoC — a solution he knows is unlikely.

Turns out Wendy was right — walking can get you thinking about problems you didn't know you had. It's a problem which, no matter how much you think about it, may take more than one bush walk to solve. Which is no bad thing.

Details: Adventure South is a DoC concessionaire offering cycling, trekking and adventure itineraries ranging from intermediate to challenging. A portion of the tour charge goes to DoC for park management. The Marlborough Sounds and Abel Tasman Trails trek starts from Christchurch and runs from November to April.

Geoff Cumming visited Marlborough Sounds, Abel Tasman National Park and Nelson Lakes National Park as a guest of Adventure South.