The spa temperature is controlled by adding more water! It’s a beautiful place to sit on a winter’s day when there’s a chill in the air, particularly if you’re covered with dust!
I wouldn’t recommend the bush spa in summer – you’re already hot enough! But then I wouldn’t recommend visiting Mungerannie in summer anyway. Best to go between the end of April and early September when the temperature’s cool enough for comfort.
The bottom of the spa is sandy, so there’s no icky stuff. Just take some thongs so you don’t get too dusty when you get out.