Bus driver Rob from Australian Pinnacle Tours barrels along at surprising speed as he scouts for a suitable dune. Then it's a slow chug up the slope, a pause at the crest, and a plunge down the near-vertical face.
It feels pretty safe strapped in the back, but still not the kind of thing you'd like to experience on Auckland's inner-city Link bus.
The dunes are constantly shifting and being re-formed by the winds blasting off the Indian Ocean. Come back tomorrow, Rob says, and you'll find a whole new landscape.
The next part of the sandy adventure is even more thrilling: sand-duning.
We pile out of the bus, wax our sand-boards, and hurtle down the slope with peals of delight. If it wasn't such hard work climbing back up the soft, boggy dune again, I could do this all day.
My day-trip north of Perth also took in the Pinnacles Desert in the Nambung National Park. Here, thousands of limestone pillars rise up to 3m out of the sand.
Scientists are still arguing about how they formed; visitors content themselves with finding funny-shaped ones.
My guide's handy at finding picture-worthy pinnacles, but not so good on the wildlife: "Bugger me if I know what that is," he says, as a mysterious reptile scuttles by.
This part of Western Australia features remarkable countryside. Tiny townships cluster around stunning white sand beaches and glassy blue-green water. The land runs almost dead flat from the coast to the Darling Ranges, and yet the surprising thing is how much it changes: from the parched north coast to the pretty, riverside state capital, and further south to flourishing vineyards and the rugged coastline of Cape Leeuwin.
Also south is Margaret River, Western Australia's newest wine region. Grapes were planted here in the Swan Valley in the 1830s, but weren't grown alongside the Margaret River until the 1970s.
Now it's dotted with resorts and bush retreats, and the pretty town of Margaret River - known locally as Maggie's Creek - entices visitors with craft shops, restaurants and cafes.
Further down the coast is Cape Leeuwin, Australia's most southwestern point, where the Indian and Southern oceans meet. The lighthouse on the cape was once manned by three families who lived side-by-side on the rugged point. Now the houses have been converted into a visitors' centre and museum for the fully automated lighthouse.
After exploring north and south of the city, I turned my attention to Perth.
The best place for a good ramble, and the best vantage point for views, is in Kings Park, which takes in the optimistically named Mt Eliza. I had to ask where the mountain was, only to be told I was standing on it. It's 62m high.
Most of the 4sq km park is native bushland, but it's also home to state war memorials and the Botanic Gardens. A treetop walkway also gives fantastic views across the city.
The other place you'll find dizzying views is the Bell Tower on Barrack Square. The modern tower on the Swan River houses bells which once rang from St Martin-in-the-Fields in London's Trafalgar Square. They were donated to commemorate Australia's bicentenary in 1988, and now peal every day in Perth.
A free lesson from the resident bellringers will leave your arms aching and ears ringing, but is well worth it.
Most Kiwis are probably more familiar with Perth's coastal neighbour, Fremantle, host of the 1987 America's Cup defence.
The port city had quite a spruce-up before the Cup, and is now an ideal spot for drinking, eating and boutique shopping.
I was given good advice by a "Freo" local: Head down the main street, cross the railway line to the waterfront and look for Little Creatures, a boutique brewery.
On a weekend, staff tell me, the cavernous pub is bursting with thirsty customers, but on a weekday afternoon, it's quiet enough to enjoy a private tasting of their four award-winning beers, and settle on the waterfront deck for a pizza in the sun.
Inside there's big windows into the brewery next door, while outside there are views over the water and a bocce pit for entertainment.
And then it's just a 20-minute train ride back to Perth. The city is a breeze to explore, and riding the free buses around the shops and cafes of Northbridge, King St and Subiaco could keep me happy for days.
But the most memorable parts of the trip were the sights I ventured further to find: the shifting, otherworldly landscapes of sand dune and desert.
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