The Tongariro River is a river in the North Island of New Zealand. The part of the Waikato River from the Waihohonu Stream, down to Lake Taupō, was formally named the Tongariro River in 1945. The river originates in the Central Plateau of the North Island where it is fed by numerous tributaries that flow off the surrounding hill ranges and mountains such as Mount Ruapehu. It then winds its way north, through the township of Tūrangi before entering Lake Taupō via a number of river mouths. The minimum volume of water flowing down the lower Tongariro River ranges from approximately 16 cubic metres per second (570 cu ft/s) to 21 cubic metres per second (740 cu ft/s). This volume can substantially increase due to catchment of rainfall by the surrounding mountains and hill ranges.

Lake Taupō is a large crater lake in New Zealand's North Island, located in the caldera of Taupō Volcano. The lake is the namesake of the town of Taupō, which sits on a bay in the lake's northeastern shore. With a surface area of 616 km2 (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 in Papua New Guinea. Motutaiko Island lies in the southeastern area of the lake.