Lake Taupo is a lake situated in the North Island of New Zealand. It lies in the caldera of the Taupo Volcano. With a surface area of 616 square kilometres (238 sq mi), it is the largest lake by surface area in New Zealand, and the second largest freshwater lake by surface area in geopolitical Oceania after Lake Murray (Papua New Guinea). Lake Taupo has a perimeter of approximately 193 kilometres and a deepest point of 186 metres. It is drained by the Waikato River (New Zealand's longest river), while its main tributaries are the Waitahanui River, the Tongariro River, and the Tauranga Taupo River. It is a noted trout fishery with stocks of introduced brown and rainbow trout.