Maori mythology says that the North and South Islands of New Zealand came from the time of Maui who was a demigod.
The story goes that he and his brothers were fishing from their canoe (the South Island) and caught a great fish and pulled it from the sea. While he was not looking his brothers fought over the fish and chopped it up.
This great fish became the North Island and thus the Maori name for the North Island is Te Ika O Maui (The Fish of Maui). The mountains and valleys are said to have been formed as a result of them hacking at the fish.
The Pandyas of South India were obsessed with naming their land parts too based on fish parts.