There are few places in the world where leaders of industry and prominent politicians sit naked together for hours on end in a sweaty wooden box, but Finland is one of them.
To avoid embarrassing mistakes when invited to “network in the nude” with contacts, it is best to read a little about what to expect beforehand. At the very least, it might help you control that startled expression.
The first and perhaps most surprising aspect of a session in a sauna is how much naked drinking goes on. Women sip flutes of champagne while ruddy-cheeked men have enormous mugs of beer. Everyone eats pickles and looks pleased with themselves.
Even if you have not done your homework, there is some advance warning: before you go through the front door of the public sauna, you will often see a large cohort of semi-naked smokers, standing on the street wearing small towels, glasses in hand, unfazed by the chill air and passing traffic.
Once inside the locker-room-cum-beer-hall everything must come off, and there must be no staring.
Full nudity is particularly important if you are with business contacts. Wearing a swimming costume in the sauna would be a faux pas akin to wearing one to play a round of golf.
Once you have stripped off, you can proceed into the shower room and, if you are in a public sauna (as opposed to a private corporate one), join the row of men or women vigorously soaping themselves.
With its bare white tiles and soapy buckets, the shower room can often look like a set in a gritty prison drama. Try not to think about this too much.
In this room there may also be a Finn receiving an ancient-Roman style body massage and scrub-down on a bench in the centre of the room.
You may find something unsettling about having oil poured on you and then scraped off by a lady with just a spatula, but have a go anyway.
The next stage, now you are clean, is the sauna itself. Most are single-sex.
If you are going into a traditional Finnish sauna, which should be made of wood, it will be hotter than you think. At this stage, the challenge is to try not to yelp or start coughing as soon as you enter. You may be laughed at if you do.
Next you have to consider whether to sit on the top shelf - the hottest part where all the real sauna aficionados are - or in the relative cool below.
Bear in mind that to sit down a rung will mark you out as a tourist and a bit of a weakling.
Do not touch the furnace under any circumstance.
The subtleties of when to throw water on the coals, when to turn the steam valve and even just how to work the contraption, should all be left to the native Finns. They have had two thousand years of practice. You will only get burnt.
Finally, when you have had enough, take a cold shower. Then go back outside for some drinking and pickle eating before repeating the process.
Private saunas can be rented for parties or business meetings. And many people have them in their houses. Altogether, there are about three million of them in a country of 5.3 million people, so they are not hard to find.