Rangaunu Harbour is a shallow harbour in the far north of New Zealand. It is situated on the east coast at the base of the Aupouri Peninsula. The name in Māori means “To pull out a shoal of fish”. With an area of 115 square kilometres (44 sq mi) it is the fifth-largest harbour in New Zealand.
The harbour entrance is a 2-kilometre (1.2 mi) wide channel to Rangaunu Bay to the north. The eastern side of the harbour is a 4 kilometres (2.5 mi) wide tombolo separating it from Doubtless Bay and connecting the hillier Karikari Peninsula to the mainland. The small settlement of Rangiputa sits on the eastern side of the harbour entrance, and Kaimaumau is located on the western shore about 5 kilometres (3.1 mi) southwest of the entrance. Unahi, at the mouth of the Awanui River, has a wharf and a fish processing plant which is now closed.
An extensive wetland, the Waihuahua swamp lies to the west of the harbour, north of Kaimaumau.
The harbour has extensive areas of mangroves, tidal sand flats and areas of eelgrass, plus several small islands, with deeper channels between.
A number of rivers flow into the harbour. Clockwise from the entrance, these are:
- Te Putaaraukai River
- Mangatete River
- Pairatahi River
- Awanui River
- Waimanoni Creek
- Waipapakauri Creek
- Waiparera Stream
Rangaunu harbour contains about 15% of the mangrove habitat in New Zealand. It is a habitat of international significance for migratory wading birds, with 10,000 birds of approximately 70 species using the harbour in the autumn. Birds observed to nest in the area include NZ dotterels, variable oystercatchers, black-backed gulls, red-billed gulls,white-fronted terns, Caspian terns, black shags, little shags, pied shags, pied stilts, white-faced herons, ducks and swans.
Dolphins visit the harbor. Other cetacean species such as humpback whales, Bryde’s whales, sperm whales, killer whales, pilot whales, and false killer whales are known to come into Rangaunu Bay and around Karikari Peninsula, but very few whales actually appear into Rangaunu Harbour. The harbor environment is an ideal habitat for southern right whales, and Rangaunu harbor might once have been a resting/calving ground for these coast-hugging whales.
Rangaunu harbor hosts a population of green sea turtles that are seasonal migrants into the harbor water regularly. Whale sharks have been seen in the harbor with slow but increasing regularities.