Regular visitors to Japan will know all about onsen. Here in the West we'd call the nearest equivalent bathhouses or Turkish baths, both of which have rather fallen out of favour in recent times. Not so in Japan, where the strict rituals involved in taking the waters in an onsen border on the religious.
It's not for everyone, that's for sure; especially if you don't like getting your kit off willy-nilly in front of strangers.
I don't mind at all, which is why I found myself sitting naked in the open-air hot springs of the Kouno-Yu onsen with a bunch of local gentlemen when, on the wooded hillside above us, a lone deer came ambling along. We sat in silence and watched as the animal sauntered across the landscape and eventually disappeared into the trees.
We were in Kinosaki Onsen, a 1400-year-old spa town about three hours from Osaka by train. There are seven public bath houses there and pretty much most of the major hotels have an onsen on site. It's a pretty, low-key place with a dainty canal running through the middle of it and it's not unusual to see groups of people in traditional yukata kimonos and wooden geta sandals clip-clopping from one onsen to the next even in deep winter with snow on the ground.
It's all very understated and elegant and civilised, and memories of our short sojourn there come flooding back as we stand outside the huge ultra-modern entrance to Spa World, an onsen theme park on the edge of Osaka's Shinsekai (New World) neighbourhood.
Yes, you read that correctly, an onsen theme park. And, really, when that piece of information comes across your dial how can you not go?
From the outside, Spa World looks very much like an office block, albeit one from the 1970s. On the ground floor there are automatic ticket machines, a gift shop, a games corner, front desk and banks upon banks of shoe lockers. An entry wristband is used to pay for food, drink and other services within the spa.
The spas are located on floors four and six, with a huge indoor/outdoor water park complex on the roof. Floor four is the Europe Zone while floor six is the Asia Zone. On even months of the year, the Europe Zone is men only and women have to make do with the Asia Zone. This is reversed on the odd months.
We are here on an even month so I am able to head to the Europe Zone while the rest of our group (all women) head to Asia.
Once the traditional rituals are out of the way – bathing and washing before going in to the spa is de rigueur – the first thing that greets you is a large circular bath overlooked by a copy of the sculpture at the Trevi Fountain. This is the Ancient Rome section.
What follows is an hour of musical chairs in which I stagger from one bath to another, one steam room to another across the huge fourth-floor area. There's a Greek section where a statue of a goddess stands guard over a herbal bath in a Parthenon-like room, an Atlantis pool (more Corinthian columns as well as an aquarium full of tropical fish) and an area designed after the famous Blue Grotto cave on the island of Capri. This last is, well, blue and there's a cave.
Off to one side is a small steam room which I discover is a salt sauna. I sit in here breathing deeply of the salt-infused steam until a Japanese man comes in and grabs handfuls of the salt in the central urn and rubs it all over his naked body. What this does is anybody's guess but it's certainly something you don't see every day. I slink away, salt-free, and head for the Finnish section where there are dry steam log cabins and solo bathtubs.
The Spanish and Mediterranean sections are on an open-air balcony, complete with waterfalls and terracotta tiles. By this time I'm not only light-headed from the constant heat but am also starting to look like some huge pink and wrinkled genetic experiment gone wrong.
Honestly, it's almost the most fun you can have with your clothes off.
Keith Austin travelled as a guest of Inside Japan Tours and Qantas.
Qantas flies direct from Sydney to Osaka's Kansai airport three times a week. Flights from Melbourne and Brisbane go via Singapore or Tokyo. See qantas.com
Inside Japan Tours chooses hotels based on the individual traveller's needs and budget. We stayed at the five-star, 1920s-style Imperial Hotel Osaka. (see imperialhotel.co.jp/e/osaka) and the new Candeo Hotel in Osaka's Namba district (see candeohotels.com), which is nominally a three-star hotel, but punches well above its weight.
In Kinosaki Onsen we stayed at Nishimuraya Honkan, a beautiful old traditional ryokan. See nishimuraya.ne.jp/honkan
Established in 2000, Inside Japan Tours offers small group tours, tailored self-guided adventures and cultural experiences in Japan. For more details visit insidejapantours.com
Spa World is open from 10am until 8.45am the next day. It's located at 3-4-24 Ebisu-Higashi, Naniwa-ku. The nearest train station is Dobutsuen Mae. A three-hour stay costs 2400 yen (about $29) and an all-day pass is 2700 yen. See spaworld.co.jp/english