The Waimangu Volcanic Valley in Rotorua is the youngest geothermal system in the world, formed as a result of the 10 June 1886 eruption of Mount Tarawera. The Earth ripped open, exposing a bunch of geothermal features but also wipping out all the plant and birdlife in the region. With beautiful volcanic craters, hot water springs, and geothermal features, it's one of the unique hidden gems you just have to visit.
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Experience: Waitomo Caves
Being a tourist in your own country feels somewhat amiss, but there are many reasons not to delegate Waitomo as solely a tourist destination