The first breath outside the air conditioned bus (Learning effect from china and Vietnam equals zero, so I spend four freezing hours without a jacket watching the green and hilly landscape passing by.) tells you why you are here. The stench of rotten eggs reminds vividly of the fact that Rotorua is build directly upon the caldera of a volcano. The whole landscape including the big lake were formed only 128 years ago during its last eruption.
Therefore the area us characterized by geothermal activity making for uncountable mud pools, damping lakes, geysers, hot water erupting from tiny holes in the asphalt and a hot pot in the hostel.
Aside from that Rotorua is famous for its strong presence of Maori culture (You can neither call them natives but they arrived here long before the British did.). Here you have the possibility to visit some rebuild villages and attend shows about cultural traditions. Anyway, I opted for the museum instead (weather was a bit to wet to walk around) and spend four amazing and informative hours there (which is quite a lot for somebody who usually tries to avoid museums).