What's this nonsense about needing to be silent in a sauna? It's the opposite. Sauna is the place where even a king can't wear his robe and crown, everyone sitting there naked, so that equality allows people to talk things more freely. Just engage the grumpy geezer in the discussion as well! I bet she would have had stories to tell. Of course this doesn't mean you should be unruly or noisy.
It would be hilarious if two or more Finns went to a public sauna in Japan, talking with each other, and the locals would get all pissed off that the gaijin can't respect the silence of the sauna.