About 350 kilometres long by 50 kilometres wide, the Taupo Volcanic Zone (TVZ) is the world's most productive area of recent silicic volcanic activity, with the highest concentration of young rhyolitic volcanoes. Mount Ruapehu marks its southwestern end, and it continues up through Ngauruhoe, Tongariro, Lake Taupo, the Whakamaru, Mangakino, Maroa, Reporoa, and Rotorua calderas, the Okataina Volcanic Complex (including Mount Tarawera) and 85 kilometres beyond White Island to the submarine Whakatane volcano. The TVZ also contains numerous smaller volcanoes, along with geysers and geothermal areas. Volcanic eruptions began here around two million years ago, with silicic eruptions starting around 1.55 million years ago, as activity shifted southeast from the Coromandel Volcanic Zone.