For health and longevity;
At present, thermal springs of France, Italy, Bulgaria, Czechia (Karlovy Vary) are world famous.
Modern research has proved that natural thermal waters have a unique composition and contain various mineral salts and trace elements.
I will share photos, but it's best to see everything with my own eyes;
Blue Lagoon, Iceland
Hot springs and spa, Bath, UK
Rogner Bad Blumau, Styria, Austria
Andorra la Vela, Andorra