The Waitoa River catchment drains the Hinuera Flats and broad southern Hauraki Plains, before converging with the Piako River in the large wetland known as the Kopuatai Peat Dome, northeast of Tahuna.
The principal island is also named Sangihe, on which lies the main town of Tahuna.
Tahuna, Waikato, a settlement in the Waikato Region of New Zealand
In the Māori language Tahuna means sandbank, likely to refer to the sandbanks along the nearby Piako River, where a Māori settlement started.