The Tāwharanui Marine Reserve, the fifth in the Hauraki Gulf Marine Park, came into being in September 2011. It protects an area of about 400 hectares on the northern coast of the Tawharanui Peninsula in the Rodney District, 90 kilometres from Auckland City.
The marine reserve replaces the existing Tawharanui Marine Park, a no take fishing area established in 1981. Scientific studies in the marine park have shown an increase in species such as snapper and crayfish.