:There are two places in New Zealand called Heretaunga. For the suburb of Upper Hutt, see Heretaunga, Wellington.
thumb|right|160px|Location of the Heretaunga Plains
The Heretaunga Plains is a alluvial plain at the southern end of Hawke Bay on the east coast of the North Island of New Zealand. The towns of Napier, Hastings and Havelock North are on the plain.
The plain was formed over the last 250,000 years from sediment deposited by the Tutaekuri, Ngaruroro and Tukituki Rivers and from coastal marine deposits. It consists of layers of gravel, sand and silt. Permeable gravel beds form aquifers and the artesian groundwater provides 85% of the requirements for public water supply, irrigation and industrial use on the Heretaunga Plains and adjacent areas.