Many official place names in New Zealand are dual names, incorporating both the original Māori place names and the English names bestowed since European settlement. Although a mixture of Māori and English names is the most common form of dual name, some places, such as Mahināpua Creek / Tūwharewhare, include Māori elements in each part of the name, and Wellington Harbour (Port Nicholson) incorporates two English names.
The practice of giving certain New Zealand places dual names began in the 1920s, but dual names have become much more common in the 1990s and 2000s, in part due to treaty settlements. Many places have names with a long heritage in each culture. For instance, a recently initialled settlement will see Cloudy Bay, given this name by Captain Cook in 1770, renamed Te Koko-o-Kupe / Cloudy Bay, with the Māori name recalling the early explorer Kupe scooping up oysters from the bay.
In rare cases, a place may be given two alternative names instead of one dual name. Prominent examples include the mountain called Mount Taranaki or Mount Egmont and the town called Whanganui or Wanganui. These places are not included in the list below.
Official place names in New Zealand are usually determined by the New Zealand Geographic Board (Ngā Pou Taunaha o Aotearoa). In cases where there have been objections to a proposed name, a final decision is made by the Minister of Lands.
A large number of dual names have been conferred not by the NZGB, but were negotiated as part of Treaty of Waitangi claims settlements and then enacted by Parliament. The 1998 Ngai Tahu settlement alone established 87 dual names, including Aoraki / Mount Cook.
Originally, the board gazetted dual names in a form where the less commonly used name was in parentheses, e.g. Taylors Mistake (Te Onepoto). In the 1990s the system was changed to separating the names with a forward slash, e.g. name1 / name2. Placing a space before and after the slash is encouraged.