Less attention-seeking than the Sky Tower, less iconic than Rangitoto, the Waitakere Ranges are the low blue border on Auckland's western periphery and easily overlooked, in both senses.

Although ruggedly beautiful, with a dramatic coastline, they seem too far away for a quick visit, too close to feel like a real destination - but all that is about to change, with the opening this week of the 70km Hillary Trail through this 17,000ha regional park.

At least that's what Stu Leighton hopes. A park ranger for 12 years, he's still a relative newcomer to this project, a long-discussed idea recorded by Sir Edmund Hillary's father-in-law, Jim Rose, the better part of 30 years ago.

"My family look forward to the time when we will be able to walk from Huia to Muriwai on public walking tracks like the old-time Maori could do," he wrote in his 1982 history of Anawhata Beach. Sir Ed and local mayor Bob Harvey kept the dream alive.

Finally, with enthusiastic support from the Auckland Regional Council, it's come to fruition, and the trail has been named after the famous explorer not just because of the family's five-generation connection to this lovely and luxuriant natural wilderness, but also in the hope of promoting the same kind of adventurousness in today's New Zealanders.

Because make no mistake, this four-day trail is much more than just a walk in the park. Officially beginning at the Arataki Visitor Centre near Titirangi, the trail picks its way along the isolated valleys and ridges that lie like a lumpy green quilt between there and the sea, working towards the coast which it follows west then north to Muriwai. One day it's hoped to extend the route all the way up to the South Head of Kaipara Harbour; but for the moment the Hillary Trail knits together a selection of the already existing 250km of walking track in the Waitakere Ranges Regional Park. "We've put in some new track to link sections, and built a new campsite at Anawhata similar to this one," Leighton says as we drive along the winding Huia Rd, leap-frogging the inland trail to rejoin it at the Karamatura Campground.

Beyond an intricately carved pou (guardian post) illustrating a local Maori legend, the campsite is an open, grassy slope surrounded by bush and alongside a rocky creek: attractive, natural - and basic. There's a small shelter with a stainless-steel bench, a composting toilet, a table, and that's it. "Whatever you need, you either carry it yourself, or you arrange to have it dropped off. That's the beauty of the trail, it's open to so many variations, and suits so many types of people, from Duke of Edinburgh Gold to mum, dad and the kids," Leighton explains.

"You can pick and choose, you don't have to do the whole thing in one go, or in any particular order."

This is just one way in which the Hillary Trail differs from the Great Walks - the Milford Track, Heaphy, Waikaremoana, Tongariro and others - which are more closely controlled and monitored by the Department of Conservation. These popular tracks are well maintained, the paths graded and gravelled where possible; there are comfortable huts along the route, often manned by rangers; there are booking systems in place; and they are more expensive to walk. By contrast, the fees for each of the three bare campsites along the new trail are just $5 each a night; and the track itself can be rough, especially after rain.

Leighton inadvertently demonstrates this as we walk along part of the Omanawanui Track towards Whatipu, when he slips on rocks made slick by a sudden summer shower - the fickle weather on this exposed coast is another reason the route should not be tackled by the unprepared.

Just minutes earlier, we were walking in dappled sunlight through a beautiful nikau grove, padding quietly along on deep humus beneath the lime-green canopy. But by the time we had reached a lookout with its stunning views of the Manukau Harbour, the neat farmland on the Awhitu Peninsula opposite and out to sea past the ridge of opposing currents at the harbour mouth, the clouds were rolling in from the Tasman and the black sands of moody Whatipu Beach darkened in their shadow.

Tucked under the hills looking out over the swamps and salt meadows is a remnant of the European history of the area: Whatipu was once a busy milling village, processing the kauri which grew thickly in the area.

When the accessible timber petered out, the Gibbons family converted their homestead to accommodation and, 100 years later, travellers can still stay the night at Whatipu Lodge. It's just one of a number of options that add to the variations possible on the standard three-night pattern for the Hillary Trail.

"People can tailor the trail to suit their own needs," Leighton says.

"We're providing the basics, and they can use them as they please. The campsites are mostly accessible by car, so they can start or finish wherever they like, they can have their equipment brought in, or they can stay at private lodges and B&Bs in the small communities they'll be passing through. They can even have a beer at the surf club if they want."

Piha is roughly the mid-point of the trail which, after Whatipu, passes ARC's Pararaha Campground before emerging from the bush at Karekare, of The Piano fame. From here it climbs up to the Mercer Bay Loop Walk, which gives magnificent views of towering cliffs and the coastline north and south disappearing in the sea-haze. Beyond Piha the trail passes through Hillary territory.

The family still use their bach at Whites Beach between here and Anawhata, where Sir Ed came to relax and recharge between expeditions, and where he took his children on explorations through the bush still fondly remembered by his son. Peter Hillary intends to be one of the first walkers on the new track, which is marked by posts bearing a picture of his father in mountaineering mode, hopefully an inspiration to those following the trail.

After Anawhata there's a choice of route for the final stage. Walkers can bear right through the "mainland island" sanctuary of the Ark in the Park, where a programme of pest control by dedicated volunteers has boosted populations of robins, stitchbird, whitehead and kokako in the area, and meet with public transport near Swanson.

Or head north to Muriwai, past more of the Maori village and pa sites that are scattered all along the trail, to the lookout over the gannet colony and the descent to the southern end of the beach, the official end of the trail.

"What we want to do is to encourage people to explore the park and enjoy it," says Leighton as we look out over the blue-green hills towards Mt Donald McLean - at 398m, it's one of the highest points in the area.

"You need to spend time here to appreciate it. You can't get that on a day trip."

He should know, after 12 years; and now so will those who spend four days or more on the Hillary Trail.