There was never a law in Finland to forbid mixed saunas. City councils set their own rules of order. Helsinki city fathers ruled mixed saunas forbidden in 28th January 1891. The rule came into effect February 2nd 1891. From that day all public saunas in Helsinki that had only a single section were open for women 12–18 and for men 18–23. During the later years the saunas had different days for men and women.
In the 1891 in the city there were at least nine public saunas which had only one section. For example they were located in Yrjönkatu 30 and Fredrikinkatu 19. This rule was also in effect when you booked a private session in any sauna. The hostess had to check that the couple entering to a private sauna was married. There is a legend that in the 1950s jewellers sold cheap rings for this…
I do not know when exactly the city of Helsinki again allowed mixed bathing — if they ever allowed. The new law of order (järjestyslaki) came into effect October 1st 2003. From this date the city rules of order were not valid anymore. The new law had no rules for mixed bathing. From this date the mixed bathing has been allowed everywhere in Finland.
I will celebrate the Helsinki Mixed Sauna Day every year February 2nd. I might spend the day at home burning a candle or eating cake. Today I was in sauna Hermanni. Thursday is the mixed day there. It was a great way to celebrate this day in sauna Hermanni! #helsinkimixedsaunaday