The two main islands of New Zealand have never had official names. Until now, that is - the situation has been rectified! The names North Island and South Island (locally always used in conjunction with a "the") are now properly registered as titles, alongside Te Ika a Maui and Te Waipounamu. No, I didn't look those up. They're well known already.
Here's the full report at the NZ Herald, and as a bonus, an introduction to real life stories recently gathered from the length and breadth of the land.