The Hauraki Gulf lies between the eastern side of North Auckland and the western sides of the Coromandel Peninsula and Great Barrier Island. It is exposed to open sea only in the north and hence possibly its name – hau meaning wind and raki meaning north. Its southern limits consists of the Firth of Thames. This firth is the northward continuation of a downfaulted rift valley which in its southern portion contains the Hauraki Lowlands. The Colville Channel between the Coromandel Peninsula and Great Barrier Island is probably another downfaulted area, whereas Tamaki Strait – between Waiheke Island and the mainland – and Waitemata Harbour are drowned valleys. These areas and indeed the whole of the Gulf were dry land during the climax of the Last Glaciation when sea level was 300 ft lower than the present level.
The sheltered waters of the gulf make it a fisherman's paradise. The even more sheltered waters of the inner part of the gulf, that is, of the Waitemata Harbour and Tamaki Strait, are surrounded by beautiful bays and beaches which make the area popular for all water sports. Between the beaches, the rocky coastlines of the Hauraki Gulf are famous for rock oysters. Eventually the Hauraki Gulf may be connected with the Manukau Harbour on the west coast via a channel cut at the head of the Tamaki Estuary.
by James Cecil Schofield, M.SC., New Zealand Geological Survey, Otahuhu.