[2] With an area of 115 square kilometres (44 sq mi) it is the fifth-largest harbour in New Zealand.

Hapū would travel across Northland to the harbour, where kapetā (school sharks) could be fished only two days in a year.

[4] The harbour was an important location for the late 19th/early 20th century kauri gum digging trade.

[6] 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.

Unahi, at the mouth of the Awanui River, has a wharf and a fish processing plant which is now closed.

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.