Both kids and adults are eagerly frolicking with mermaid-like flippers in blue swimming pool waters in the latest craze to hit the Nordic country sometimes referred to as "the land of thousand lakes".

Finland's first Mermaid School has opened classes in swimming pools in Espoo and Helsinki, national Finnish broadcaster Yle reported. The mer-instructors teach their students how to swim like the fictitious folklore creatures using special gear, a distinctive mermaid tail that combines a giant monofin flipper with fabric from the waist down.

The mermaid swimming (or "mermaiding") classes at the commercial Sporttaamo leisure centres in Espoo and Helsinki are run by swimming instructor Maija Möttönen. While it's difficult to estimate exact numbers, Möttönen nevertheless argued that her clientele has grown exponentially.

By Möttönen's own admission, virtually anyone is welcome, as her classes don't discriminate along gender or age lines. The only requirement is that one can swim at least 50 metres.

"I believe last year there were more kids who were mermaiding, but we now we have also a lot of adults who have taken up this hobby", Möttönen told Yle. "I would say that last year there were maybe 20 adults. Since then, I have had over 100 new mermaid students, most of them adults".

Markus Parviainen, a construction worker from the city of Vantaa, admitted to first being a bit nervous, as he perceived this pastime to be "for little girls". Still, he joined the group and is happily swishing his mermaid tail "to become an example for guys".

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Möttönen said she got into mermaiding after first reading about it online. Since then, she has become part of the international mermaiding community, eagerly sharing the pictures of her exploits with fellow mermaids and mermen. Running mermaiding classes has become the apogee of a lifelong dream for Möttönen.

"When I was a kid I wanted to have my own gills, so that I could be underwater and live there", Möttönen recalled. "When I bought my first tail it was just a hobby, and now it's my work, so it's a kind of dream come true for me!"

Finland's recognisable moniker "the land of a thousand lakes" is in fact a severe understatement, as the Nordic country has about 188,000 lakes. Despite mermaids mostly being associated with Disney's classic "Little Mermaid" or Danish writer Hans Christian Andersen's fairy tale, Finland has its own representation of the mermaid myth. Given the infinitude of lakes, it is little surprising that the "vetehinen" (or "merman") is a fixture of Finnish folklore. Incidentally, "vetehinen" was also the name of the submarine class in the interwar period. In Kalevala, the Finnish national epic, a girl named Aino drowns herself rather than marrying a wicked old man, thus becoming yet another representation of mermaids in Finnish folklore.