In a dimly lit wood panelled room, naked men sit in silence, sweating. One beats himself repeatedly with birch branches. Another stands, takes a ladle of water and carefully pours it over the heated stones of the stove in the corner.
There is a hissing noise.
Within seconds a wave of moist heat creeps up around your ankles and over your legs before enveloping your whole body. Your pores open up and sweat covers you from head to toe.
This bathing ritual has been performed across Finland for thousands of years, ever since the first settlers dug a ditch in the ground and heated a pile of stones. Water was thrown on the hot stones to give off a vapour known as loyly.
Each sauna is considered to have its own character and its own distinctive loyly. The better the loyly, the more enjoyable the sauna.
For those working in the fields in harsh conditions, the sauna provided welcome relief to wash and soothe aching muscles.
These warm wooden rooms could be used at lower temperatures too, and were at the heart of the major events of a Finn's life.
Women gave birth in them because the walls of traditional smoke saunas were lined with naturally bacteria-resistant soot, making them the cleanest room in the house.
Saunas were also the place for purification rituals before marriage, and the bodies of the dead were washed and prepared for burial on the wooden benches.
For many Finns the sauna was the holiest room in the house and the one most closely associated with their wellbeing.
"Finns say the sauna is a poor man's pharmacy," says Pekka Niemi, a 54-year-old from Helsinki, who spends about three hours a day in the sauna, six days a week. "If a sick person is not cured by tar, spirits or sauna, then they will die," he adds, quoting a Finnish proverb. ("Spirits" here means strong alcohol, while tar was historically used as an antiseptic.)
Today, Finland is a nation of 5.3 million people and 3.3 million saunas, found in homes, offices, factories, sports centres, hotels, ships and deep below the ground in mines.
