The Hot Springs at Ranong
The water at Ranong Hot Springs comes out of the ground at 65° C, and is piped to pools where you can dip your limbs into (if you can stand the heat!). The water is also piped around the concrete floor of a roofed area, where you can lay on the concrete to heat your body.
This is alleged to have healing powers, for such ailments as arthritis and other problems. The areas here are free to use.
Close by the springs you can get a Thai massage, food, drink and souvenirs.