Rotorua is known for it's insane amount of geothermal activity... every holiday park and hotel boasts it's own mineral baths and sulphury steam can be seen rising out of the ground every where you look.
We got free tickets to Hells Gate (New Zealand's yellowstone).. so we checked it out... it was ok, but nothing compared to what is brewing in Idaho's side yard....
(we were just grateful we were not one of the people who had to pay $30 to walk around this smelly, boiling mud bath)