lake in north-central North Island, New Zealand, and largest of a group of about 20 lakes, including Rotoiti and Tarawera, that were formerly called the Hot Lakes. The lake is pear-shaped and measures 7.5 miles (12 km) by 6 miles (9.5 km). Lake Rotorua (Maori: “Crater Lake”) has a total surface area of 31 square miles (80 square km). Lying at an elevation of 920 feet (280 m), it fills a crater probably created by an immense volcanic explosion and reaches a depth of 85 feet (26 m). The lake drains a 203-square-mile (526-square-kilometre) basin and discharges through the Ohau River to Rotoiti. Subsurface thermal activity, the basis for the health-spa city of Rotorua (southwest), discolours the lake's water in places. Volcanic Mokoia Island, sacred to the Arawa Maoris, lies in the lake. The first European to visit the lake was Peter Tapsell, in 1830.