Alalauteilla
Bottom bench. It is the coolest seat in the room and nobody admits to choosing it on purpose.
The sauna runs on about eight words: löyly, kiuas, lauteet, vasta, vilvotella, riittää, saunavuoro. That is an afternoon's work, and it covers most of what gets said in there.
From Could You Survive a Finnish Sauna? - 6 lines of real spoken Finnish on Finnish IRL.