Taipei - With a towel wrapped around his head, Jen Chen greets his friends as he slips into a pool of hot water and hums his favourite song.
Like many men, visiting this hot spring in Peitou - the oldest in Taiwan - is a ritual he has been performing for decades.
Only now he finds himself surrounded by women and children as the island's once sleazy bath-house culture undergoes a transformation.
Nostalgically, Chen closes his eyes and hums a song called Yunojima Elegy, about a man seeking comfort in a bathhouse after he is ditched by his lover.
"That was a Japanese song very popular more than half a century ago," Chen, 72, recalls as sweat droops down his face while steam with the smell of sulphur rises from the pool.
"At that time, it took only three cents to have a hot spring bath," he adds wistfully.
The spartan public bathrooms in Peitou are the most famous in Taiwan, where hot spring culture is more than a century old. Its development dates back to 1893 when a German businessman discovered hot springs there and set up a spa.
When Japan colonised the island two years later, the culture of hot springs started to spread across the island and during the 50-year occupation, Peitou flourished as the premiere spa destination.
Even so, housewives and children from outside the area were reluctant to stay in hot spring hotels.
"Peitou used to be a place for men only. They came here mainly for drinking and having sex while enjoying hot springs," says 46-year-old Yeh Su-hung, a resident of Peitou.
But things have changed since the late 1990s, with Peitou emerging as a popular leisure spot for families.
"Time flies. Everything's changed," says Chen, a retired factory owner, as he sits in the tub of 40°C water.
The pools are now surrounded by several luxurious high-rise hot spring hotels nestling on the foothills of the Tatun group of 20 volcanoes north of Taipei.
Windy Yang, a noted writer nicknamed "Spa Lady", is among the many women who now enjoy bathing in hot tubs at Peitou and elsewhere.
"Japan's 'onsen' (hot spring) culture has had a far-reaching influence on the development of the local hot spring industry," she says, adding that it has become a recent leisure fad, as it is believed they are good for health.
"I suffered from some injuries like tennis elbow and wrist strains, but these have greatly improved over the past five years," says Yeh, who pays T$40 (US$1,23 or about R7) for each stay of up to 150 minutes at Peitou's spa.
"However, it would not help if you don't soak hot springs enough. I do it five days a week," he advises.
A driving factor behind the gentrification of spas was the government's adoption of a five-day work week in 2000, says Chen Hui-tsung of the private Hot Spring Tourism Association Taiwan.
"With parents having more time, they now look for good places fit for whole families. Parents would by no means take their children to hot springs where sex services are available," he says.
Programmes aired by several cable television channels about Japan's famous hot spring resorts and cuisine are also fuelling the interests of leisure seekers and entrepreneurs.
"Spa and hot springs investors have found the huge business opportunities from the changes" in the perception of hot springs, says Chen.
The sector has attracted investment worth billions of United States dollars to construct some 150 large resorts, hotels and restaurants in the island's 20 hot spring areas, he says. In Peitou alone, there are more than 20 hotels.
Those who prefer to soak in privacy rather than a communal public bath, there are luxury resorts in Peitou and places such as Wulai, a mountainous aboriginal scenic spot less than an hour of drive from the capital.
"Once they are here, our clients will definitely appreciate the 'value' of our service," Jesse Cheng, general manager of the Spring Park Urai Spa & Resort, says, referring to its French cuisine, spa facilities and views of the Nanshih River.
The small, upscale resort has had an occupancy rate of around 70 percent since it opened in 2001, despite a price tag of T$26 000 (about R4 770) per night in one of its suites.
Private baths suit "Spa Lady" Yang who says she likes "nude bathing" because "it helps strip off the worldly burden and gives me a kind of feeling like that of a foetus in a mother's womb".
Yang, who has tried around 500 hot springs in Japan over the past 30 years, says Taiwan has as many types of hot springs as Japan and the sector is likely to prosper.
Taiwan touts mud springs in the southern Kuanziling area and undersea spas on the offshore Green Island.
However, unlike Japan, where hot spring tourists stay overnight or longer, many Taiwanese pop in for an hour or two.
"That's because in Japan, hot springs are located in remote areas and it may take several hours for tourists to drive. Whereas in Taiwan, the time of journey from Taipei to hot spring areas is less than an hour," the association's Chen says.
"That's a niche of Taiwan's hot springs."