Extensive ignimbrite sheets spread east and west of the Taupo Volcanic Zone centred on the huge dormant supervolcanic caldera Lake Taupo, the largest lake in New Zealand, which last erupted 2000 years ago. The volcanic area includes the three active peaks of Mount Tongariro, Mount Ngauruhoe, and Mount Ruapehu in the south, and extends beyond Rotorua in the north reaching almost to the Bay of Plenty coast. North of Tongariro is the volcanic Mount Pihanga. The western boundary of the plateau forms an escarpment beside the Mamaku and Kaimai Ranges, but further south is less distinct. In the east, the plateau runs up to the foot of the Ahimanawa, Kaweka and the fertile Kaimanawa mountain ranges. Finally, west of the plateau stands the volcano Mount Taranaki (in Egmont National Park).