Around the U.K., the number of public sauna sites has jumped from 45 in 2023 to 147 so far this year, according to the British Sauna Society.

It may be winter and there may be a biting chill in the air, but the dozen men and women who have packed this small sauna room in east London are happily sweating away in their swimwear. It’s more than 194 Fahrenheit in here — and it’s about to get even hotter.

Sweating it out in communal spaces for relaxation, physical or mental therapy and socializing has long been a staple of many cultures around the world.