Why does rotorua smell?

Answer 1

Rotorua's abundant geothermal activity (hot pools, geysers, mud pools, etc.) results in large amounts of sulphur compounds, and especially hydrogen sulphide (which smells of rotten eggs) to be released into the atmosphere.

The smell might be overwhelming to a foreigner, but if you live there or visit regularly, you get used to the smell.

Answer 2

Rotorua (two lakes) lies on the Taupo Volcanic Zone, New Zealand, and is locally the site of surface geothermal activity. Geysers, boiling pools and hot mud pools. The geothermal fluids contain H2S, the familiar 'rotten egg' smell.

This is a gas to which the human nose soon becomes insensitive, and because this gas is poisonous, this can cause problems, including death. The sulphide gas tarnishes silver very heavily, and in older times when telephone relays were silver-clad, the local telegraph station used platinum-coated contacts on the relays.