Wai-O-Tapu is one of the numerous thermal areas in and around Roturua. The main attraction of this one probably is the Lady Know Geyser which erupts every day at 10:15am - regardless of daylight saving time or not. The reason for this precise timing is that a soap-like substance is thrown into the crater, causing the surface tension of the water in the geyser to decrease and therefore triggering the eruption. If nobody added the soap it would still go off by itself at an interval somewhere between 24 and 36 hours but with the precise timing it's obviously far more appealing to tourists.
The rest of Wai-O-Tapu (Sacred Waters) is a thermal park with crater lakes of all colours, mud pools and other forms of volcanic activity.