Lake Rotorua partly fills the Rotorua caldera. This was formed about 230,000 years ago by a huge ignimbrite eruption. Mokoia Island, in the centre of the lake, is a rhyolite dome, formed after the caldera collapsed. Lake Rotorua was originally larger. Rotorua city, in the foreground, is built mainly on the old lake bed.
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Photograph by Lloyd Homer
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