Waiotapu - Lady Knox Geyser

Waiotapu's top attraction is the Lady Knox Geyser, which spouts with almost unvarying punctuality at 10.15am and sends a jet of water high into the air.

This punctuality is achieved, however, with a little help. Soap powder must be thrown into the water: the sodium carbonate therein decreases the surface viscosity and sets the geyser off. This was discovered by convicts who used soap to do their washing in pools of thermal water.