Every morning, a rocky grey vent called the Lady Knox Geyser spews water for a captive audience. Far from a strange local ritual, the geyser is one of the star geothermal attractions at Rotorua’s Wai-O-Tapu Thermal Wonderland. It erupts without fail—after being induced with soap—to heights of 30 to 65 feet (9 to 20 meters).