100°C is a quite hot one. It could hurt your nose and ears a bit, especially if they having a steaming session.

The cold water (normally ~10°C) does not hurt at all. The first minute your brain is not able to differentiate the temperature at all. After that it gets quite quickly into: ohh I should leave!

Btw: you should try sauna at some point. Especially with the steaming it’s amazing. There are also milder ones with ~80°C, I would recommend at the start.