Motorcycle tour in Ha Giang, Vietnam: Fairy bosoms and moon rocks

Below me, the world is split into two unmatched halves, the odd creation of a pretty undecided God. On the left flank of the valley, rocky grey crests soar high from deep gorges, running after each other like petrified waves on the surface of a craggy sea. But to the right, a stark contrast of rolling green mountains cast constellations of viridian paddies as far as the eye can see. It's as if Mother Nature had randomly picked two wrong jigsaw pieces, interlocking them at her odd will.

I'm observing this puzzle from a strip of high-altitude asphalt, while my rental Honda Wave sputters uphill. The road cuts through limestone walls like a dark gash in an ash-toned body. I feel like a tiny anchovy lost in the middle of this solid rock ocean, so awestruck I can just inch forward and look beyond the cliff to my left, gulping down at every hairpin bend.

This is all in a day's work for those who dare venture in the Ha Giang region. Vietnam's northernmost corner is a place of misty landscapes strewn with conical limestone crags, deep gorges and mountain tribes who have made these ancestral highlands their barren homeland. If I squint at the horizon hard enough, China's Guanxi province gazes back at me from behind a curtain of puffy clouds.

What I consider south-east Asia's most scenic road trip starts right beyond the small and frankly unattractive town of Ha Giang, an eight-hour bus ride north of Hanoi. It's a wild 320-kilometre motorbike loop along a series of divine mountain switchbacks, connecting the villages of Tam Son, Yen Minh, Dong Van, Meo Vac and Bao Lac. This route can be leisurely completed in three days, but the beauty of the scenery commands for longer stays – especially because Ha Giang's back roads are still under most travellers' radars.

Resting my wheels at the top of a ridge overlooking a bundle of saw-toothed limestone peaks, I can't say I'm not glad that Ha Giang remains a hushed secret. But I also wonder why. No doubt, it can't be for the special (but very rarely checked) permit required to visit – most of the region's hotels and guesthouses can get it for a mere $20. And with new accommodation options, a slew of refurbished local restaurants, and the crucial arrival of ATM circuits, travellers should be flocking in as in nearby Sapa. I reckon people don't come because to enjoy this stunning yet forlorn slice of North Vietnam, one must rent a motorbike and do the hard work: riding alone against the wind from Ha Giang to the villages of Meo Vac and Dong Van. To me, negotiating one hairpin bend after the other is certainly more rewarding than sharing a touristy mountain village with busloads of other tourists.

On my first day, I set off from Ha Giang's town limits, and the road immediately starts climbing through forested hills until the Dong Van Geo Park, inscribed by Unesco in 2011. After a couple hours rising along cliffs flanked by deep mountain gorges, I stop at a cluster of sharp pinnacles nicknamed "Moon Rocks". I meander around, stretching my legs from stone to stone, exploring the unnatural landscape. When I get on my bike once again, I end my ascent marvellously at Heaven's Gate Pass: once upon a time, this was the border of the H'mong kingdom, stretching all the way to Dong Van. To mark this boundary, the French colonisers built a huge, 150-centimetre-thick door on the top of this mountain. Today, there's only a battered sign in English and Vietnamese, shouting "Quan Ba Heaven Gate" to the ears of unforgiving mountain winds. But from this vantage point, the views over the Dong Van plateau are simply perfect.

Descending to the village of Tam Son, I find myself gaping at a series of mound-shaped hills. Two of them are almost identical, and rise very next to each other … very much like the uncovered breasts of a buried giantess. "You are right: locals call them the 'fairy bosoms'," explains another young Vietnamese motorist who stopped to snap a picture. I hope he's joking about the bosoms, but he's not. He's travelling for work, to check the radio towers that connect these highlands to the world. We share laughter and a table in Tam Son, ordering fried noodles and beer, a nice interlude before parting ways along the serpentine Mien River. I'm speeding to Yen Minh, my final destination for the day. As the road rises again from the valley, the horizon breaks into a forest of limestone peaks extending all the way to China.