HELSINKI (AFP) - Is stripping down and getting sweaty with strangers your kind of thing? In Finland, despite an astounding 2 million private saunas, the hottest trend sweeping the sweat tank loving country is public saunas.

They’re Helsinki’s coolest spots this summer, drawing Finns and tourists of all ages to unwind on wooden benches in slick waterfront locales where the mercury hits at least 80 degrees Celsius.

A trendy new boutique sauna called Loyly (Finnish for “Steam”) opened its doors on the capital’s shoreline in May and was such an instant hit that an online reservation is a must on sunny days.

On a recent visit, a group of men and women who went to university together celebrated Linnea Remes’ 27th birthday by having a sauna -- a normal thing for friends in Finland where saunas are an integral part of daily life and all major celebrations year-round.

Remes has a sauna at home up to four times a week so her birthday choice was not for want of a good sweat.

“We thought that this was a fun way to pass time together and enjoy ourselves,” Remes told Agence France-Presse on the seaside terrace where the group cooled off before another round in the hotbox.

Finnish sanctuary

While Finns strip down to their birthday suits in their private saunas, the public ones either offer different rooms for men and women or require swimsuits in unisex saunas.

The sauna can be a moment to destress or a complement to a good workout. A couple of rounds is typical, with a cool shower and maybe a drink in between, or preferably a dip into a lake or the sea. In winter, a roll in the snow is even better.

But saunas have been used for bigger goals -- sealing business deals and even serious diplomacy. During the Cold War, Urho Kekkonen, who served as president for 26 years, negotiated with Soviet diplomats in the sauna of his official residence.

It is precisely the social aspect of a public sauna that explains its countrywide renaissance.

Over the centuries Finns used saunas for washing, relaxing and even giving birth. But the modern luxury of running water in virtually all residences spelled the demise of the popular old public sauna as people started installing their own private hot rooms.

Nowadays most houses and new apartments in Finland come with a private sauna. Statistics Finland estimates there are more than 2 million saunas for a nation of 5.5 million people.

At the same time, 1 in 5 Finns today lives on their own.

Common experience

“Many people live alone nowadays, but yearn for that sense of community and common experience. A sauna is the best for that, an intimate place where you can exchange ideas with whomever happens to sit next to you,” said Raoul Grunstein, head of Allas Sea Pool, another new public sauna and spa set to open this month.

Grunstein has such faith in the appeal of public saunas that he and his partners invested 10 million euros ($11 million) in the spa, which has three saunas and three pools floating in the sea right on Helsinki’s main market square opposite the presidential palace.

Like Loyly, the facility boasts striking Nordic design and architecture.

Loyly’s owners -- lawmaker Antero Vartia and actor Jasper Paakkonen, known to international audiences for his role in the Irish-Canadian TV series “Vikings” -- spent big, investing 6.3 million euros in a cubic design that holds three traditional wood-heated saunas, one of them a chimneyless smoke sauna.

“The city’s tourism authorities have told us they believe this will shortly become one of Helsinki’s top three attractions,” Paakkonen said.

At Loyly’s, Priya Selvaraj, a 42-year-old professor visiting from Chennai, India, marveled at the experience, including a courageous post-sauna dip into the Baltic Sea, where water was a downright chilly 11 degrees Celsius.

“I have taken sauna treatments back home in the southern part of India ... and it’s not new to us,” she said, “but to have a country or a city where it‘s thriving on spas!”

Burgers and saunas

The sauna’s appeal is so strong in Finland that even the U.S.-based fast-food chain Burger King wants its Finnish shops to partake: It recently opened a sauna at one of its Helsinki restaurants, available for groups upon reservation.

The revival of public saunas goes back to 2011 when a few Helsinkians built Sompasauna, an unlicensed sauna made of waste materials in the middle of an old harbor-turned-construction site.

The city‘s first reaction was to tear it down.

But the free-of-charge, mixed and nude sauna appealed to many and its fans have rebuilt the small shack every spring.

This year the city honored it as Helsinki’s “cultural act” of the year.