Lake Taupo itself was created by a massive eruption 26,500 years ago. The caldera — the collapsed and subsided basin left after the huge eruption — became today's lake.

But Taupo did not die. The 485-square-mile caldera let loose again in the year A.D. 181, with estimates of ash and magma reaching as high as 22 cubic miles. That's on the order of a hundred times more than Mount St. Helens.

Today Lake Taupo still shows signs of life, which New Zealanders have put to good use. Ample hot springs and other hydrothermal activity enable New Zealand to generate about 8 percent of its electricity at a geothermal plant on the north side of Lake Taupo, at Wairakei.