Port Nicholson, also known by the Maorified name of Poneke, is a large natural harbour at the southwestern end of New Zealand's North Island.
Port Nicholson is an arm of the Cook Strait, covering some 70 km2, with a narrow two-kilometre wide entrance at its southern end between Pencarrow Head and the Miramar Peninsula.
The harbour is of seismic origin, and a major earthquake fault lies along its western shore. At the northern end of the harbour lies the narrow triangular plain of the Hutt River, which largely follows the line of the earthquake fault to the northeast. The city of Lower Hutt is located on this plain.
At the southwest of the harbour are two large bays, Evans Bay and Lambton Harbour, the latter of which is the port of the city of Wellington, New Zealand's capital city. The city's suburbs spread around the hills overlooking the west and southwest of the harbour, and across the small coastal flats to the Miramar Peninsula.
To the east of the harbour lie several small bays, most of which are populated by small coastal communities. the largest of these townships is Eastbourne, directly to the east of the northern tip of the Miramar Peninsula.
Three small islands are located in the harbour. To the south, close to Eastbourne, is Ward Island. Further north, close to the centre of the harbour, is the larger Matiu/Somes Island, to the north of which is the tiny Mokopuna Island.
The entrance to the harbour can be quite dangerous, especially since the Cook Strait to the south is notoriously rough. Close to the harbour's entrance lies Barrett's Reef, its rocks breaking the water's surface at low tide. It was here, in 1968 that the inter-island ferry Wahine grounded during a storm, with the loss of 51 lives.
The early Maori name for the inlet, is Te Whanganui-a-Tara (either "The big harbour of Tara" or "The big harbour between the peaks"). The term is now usually used to represent the city of Wellington itself.
During the early years of European colonisation, the Port became a focus for settlement. The original site chosen for what is now the city of Wellington was at Petone, close to the foreshore of Lower Hutt. A settlement was established there in early 1840, but the swampy land was unsuitable for development, and the settlement (originally called Britannia but soon changed to Wellington) was moved to the present site of Wellington city later the same year.