Taupo, Lake (tou`pō), largest lake of New Zealand, 234 sq mi (606 sq km) and 552 ft (168 m) deep, in central North Island. Originally fed by over 20 streams, the lake is drained by the Waikato River. Lake Taupo is situated within a volcanic caldera, c.22 mi (35 km) across, which was formed by the massive explosive eruption of the Taupo volcano c.25,000 B.C., and it is flanked by volcanoes. The last major eruption of Taupo was c.A.D. 200.