Your guide to the world's best hot springs, from Hungary to NZ

I'm headed for the onsen at a traditional hotel in a mountain town in Japan but I've committed a terrible faux pas - coming down from our room wearing my husband's yukata (robe). It took me a while to cotton on when one of the staff rushed over in a fluster.

"Miss Natascha," she says. "I am so sorry; this yukata is not right for you - it is too big."

"Oh no, honestly, it's fine, no problem," I respond blithely.

But she won't have it and gently escorts me back up to our room, where I realise, when she shows me a "smaller" one folded on the chair, that I have inadvertently picked up a masculine patterned yukata - my husband's rather than mine. Shame averted, I go down to the onsen, where there is just myself and a young woman, naked, washing herself using a wooden bucket sitting on a small stool in front of a mirror. I do the same, lathering my hair, scrubbing my skin and rinsing several times, but even when I am squeaky clean, she is still going, so I hop into the hot water. She never does get in with me and I can only surmise I've committed some other unwritten bathing sin.

Not all thermal spring bathing experiences are so fraught with possible mis-steps, although it's worth learning the local etiquette if you're keen to experience the healing power of naturally heated mineral water. Here are a few places to try.

The mineral-rich hot spring pools at the foot of Gellert Hill in Budapest were known to locals since the 13th century, but it was the Ottoman Turks who occupied the Hungarian kingdom in the 16th century, who built the bathhouse. In the 1800s, more refined buildings were constructed to enable access to the healing waters. They were demolished to make way for the Liberty Bridge and rebuilt in 1918 with an art nouveau aesthetic. The famous wave pool was added in 1927.

It's a huge, beautifully ornate and highly atmospheric complex of small and larger pools and treatment rooms. It's also a bit maze-like, so grab a map at the entry. Since 2013, when men and women's pools were combined, bathers for bathers are required. You'll also need to bring thongs (the flip-flop type) and a bathing cap if you want to go into the wave pool, although you can rent one along with a swimsuit if need be. gellertspa.com

While places such as Saturnia in Tuscany seem to pop up on the social feeds of every influencer on a European "vacay", serious spa-ists go to Ischia, a volcanic island rich in healing geothermal water. Just off the coast of Naples and neighbour to the more glamourous (and financially ruinous) Capri, many of Ischia's hotels or resorts have their own spas, having tapped into the water; look for the word "terme".

Others are public, such as Poseidon or Negombo thermal parks, where you pay an entrance fee and can spend a half or a full day dipping in and out of the therapeutic hot pools. And, pssst... here's a local secret not many people are privy to: you can bathe for free at the natural springs in the bay of Sorgeto where the thermally heated water comes up through sea floor into the rockpools. ischia.it

One of the more unexpected places to find water is the driest place on the planet, but at 3500 metres above sea level in a beautiful valley at the bottom of a canyon on a nature reserve in Chile's Atacama Desert is the Puritama Hot Springs. The water has a significant concentration of minerals, including calcium, magnesium, sodium and boron, bubbling into right pools of different sizes at temperatures at between 28 Celsius and 31 Celsius. The rock pools, some with small waterfalls are fringed by turkey grass and maintained as naturally as possible to fit it with the surrounds.

It's small, low-key and as special an experience as you could have, with views of snow-tipped volcanoes and the red soil and wind-eroded rock sculptures of the desert. termasdepuritama.cl

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On New Zealand's North Island, the mineral-rich waters (and mud) of this area have been used as a cure for skin and muscle ailments since the 1800s, when the original bathing pools of the Polynesian were built here. Of course, the Maori, who are guardians of the geothermal pools and have a name for each of the springs in Rotorua, knew of the healing powers of the hot mineral water for skin and rheumatic complaints long before then.

Polynesian Spa's 28 pools, heated to different temperatures are drawn from two natural springs, one acidic, which is recommended for sore muscles and general aches, the other, being alkaline considered good for skin complaints. Book one of the private pools overlooking the lake where you can lounge on geothermally-heated lounges between dips and take in the lake views. polynesianspa.co.nz

There are hundreds of spas, known as "onsens" in volcanically active Japan, in all different formats. Writer, Japan expert and host at Zenbu Travel, Jane Lawson, says her preference is always for a private onsen (also less chance of committing a publicly visible social blunder) and that the Abba Resorts Izu in Shizuoka fits the bill.

"It's a sprawling property with a beautiful ryokan, featuring both traditional and contemporary rooms and restaurants," says Lawson. "Our stunning villa had a private outdoor onsen in the garden, which we enjoyed with sake, relaxing music and a sprinkling of snow."

And her etiquette tip, whether private or public, apart from washing down before hopping in, don't drink alcohol. "I promise we only sipped," she says. zagyosoh.com/lang/en/x

Hepburn Bathhouse and Spa in Victoria's Hepburn Springs has both shared and private thermal pools. See hepburnbathhouse.com

Peninsula Hot Springs on Victoria's Mornington Peninsula has thermal pools, an underground sauna and Turkish steam bath. See peninsulahotsprings.com

Alba Thermal Springs, also on Victoria's Mornington Peninsula, has shared and private pools, including a rooftop salt float pool. See albathermalsprings.com.au

Bitter Springs, in Elsey National Park near Katherine in the Northern Territory, are a series of photogenic jade-coloured thermal pools. See nt.gov.au