Lady Knox Geyser The 10:15 eruption of the Lady Knox Geyser. The geyser is induced to erupt daily at 10:15am by dropping a surfactant (likely some sort of soap) into the opening of the vent
This image is from the presentation "Lake Taupo, Rotorua, Hawke's Bay and Tongariro - Middle Earth Meander - New Zealand 2016".