The North Island or Te Ika-a-Māui (Māori) is one of the two main islands of New Zealand, separated from the slightly larger but much less populous South Island by Cook Strait. The island's area is , making it the world's 14th-largest island. It has a population of 

Twelve main urban areas (half of them officially cities) are in the North Island. From north to south, they are Whangarei, Auckland, Hamilton, Tauranga, Rotorua, Gisborne, New Plymouth, Napier, Hastings, Whanganui, Palmerston North, and Wellington, the capital, located at the south-west extremity of the island. About % of New Zealand's population lives in the North Island. 

Although the island has been known as the North Island for many years, in 2009 the New Zealand Geographic Board found that, along with the South Island, the North Island had no official name. After a public consultation, the board officially named the island North Island or Te Ika-a-Maui in October 2013. 

In prose, the two main islands of New Zealand are called the North Island and the South Island, with the definite articles. It is normal to use the preposition "in" rather than "on", for example "Hamilton is in the North Island", "my mother lives in the North Island". Maps, headings, tables and adjectival expressions use North Island without "the".
what are some other urban areas or cities on the island?
From north to south, they are Whangarei, Auckland, Hamilton, Tauranga, Rotorua, Gisborne