One of my favorite past time is onsen or Japanese hot-bath. But when I was in Japan in summer 2022, sauna, which is relatively late introduction to bathing ritual is super hot in Japan. In every single onsen, almost everyone would bath in the hot heat of sauna.
I generally do not prefer sauna, as I found the heat, which can go up to 100 celcius, is oppresive. But this practice has been very popular in Nordic countries, especially Finland (thus the term Finnish sauna) and Iceland. In Iceland, there is a beautifully design Blue Lagoon that is hosting a few interconnected geothermal baths. The sauna is extremely expensive and offer multiple treatment such as the 5-hour Blue lagoon retreat, that includes entrance to Retreat Lagoon (a private lagoon), five spaces, and Blue lagoon ritual that seemed to combine practice of scrubbing with beneficial minerals, lava mud, and silica.
Sauna come from Finnish language. It is a ritual associated with well being, relaxation, and often combined with the practice of dipping in natural lake.
In Japan, onsen often hosts a combination indoor and outdoor pools and saturated with beneficial minerals. All onsen that I have been to, has at minimum a hot pool, cool pool, and a jet pool - as well as nowadays a sauna room.
