Lake Rotokākahi or Green Lake, is one of four small lakes lying between Lake Rotorua and Lake Tarawera in the Bay of Plenty Region of New Zealand's North Island. The others are Lake Tikitapu (Blue Lake), Lake Ōkāreka, and Lake Ōkataina. All lie within the Ōkataina Caldera, along its western edge.
thumb|The Arawa fighting contingent, Rotokakahi (Green Lake), Aotearoa-New Zealand, 1870
Geography
The lake flows to Lake Tarawera via the Wairoa Stream (also known as ) past the buried Te Wairoa village and its Wairere waterfall. The Wairoa Stream when it leaves Lake Rotokākahi has a mean flow rate of but it picks up subsurface water and tributaries so when it enters Lake Tarawera it has a mean flow rate of . It contains a small island in its western arm, Punaruku Island and its southern arm has a larger island Motutawa Island. Its trophic level index was 3.6 in 2014 which was a decline and relatively high for a local lake.
Motutawa
This small island in the lake is notable as the site of the 1822 slaughter of a part of Ngāpuhi, as an act of vengeance for relatives killed by the same Ngapuhi warriors in Te Totara, Thames.