The Tokaanu Thermal area sits on the southern shore of Lake Taupo and is part of the Tokaanu-Waihi geothermal field. It is an alkali-chloride, high-temperature system that forms the southernmost fringe of the Taupo Volcanic Zone. Sinter cores from the park suggest this process has been active for at least 6,000 years, though the surface has changed considerably over time. Monitoring since the 1880s has recorded a fairly consistent decline in spring temperatures and discharge rates, and the once extensive open sinter flats have largely been overtaken by vegetation and bog.
What remains is still geologically interesting. The short loop track passes springs with sinter rimmed basins, mud pools, steaming ground, and a small geyser (Taumatapuhipuhi) which reportedly reached over 30 metres in the 19th century but now erupts to little more than a metre or two at intervals of a few minutes. The thermal features sit alongside the cold Tokaanu Stream.
Beyond the main tourist area there are some additional geothermal features, most notably two remarkably active, circular mud pots, with the larger spanning approximately 7m by 7m.
