They are lithe and playful, but also devastatingly effective predators, working around and through schooling fish such as kahawai, soury and pilchard.

In all, there are 25 species of marine mammals found in the Hauraki Gulf, almost a third of the world’s marine mammal species.

The Hauraki Gulf Marine Park is New Zealand’s only gazetted national park of the sea. Within it are six small marine reserves—Pollen Island beside the north-western motorway, Te Matuku at the bottom end of Waiheke, Long Bay, Goat Island and Cathedral Cove on the Coromandel Peninsula. All are important, but none are large enough to have an impact on the health of the gulf. New reserves are proposed, but it is unclear whether they will be no-take or allow fishing.