According to Māori tradition, Paikea is an ancestor of Ngāi Tahu and Ngāti Porou, Māori tribes in the South Island and east coast of New Zealand's North Island. Paikea is the name assumed by Kahutia-te-rangi because he was assisted by a whale such as a southern right whale (tohora) or humpback whales (paikea) to survive an attempt on his life by his half-brother Ruatapu.
Ruatapu became offended when his father Uenuku elevated his older half-brother Kahutia-te-rangi (later known as Paikea) ahead of him. When Ruatapu was about to use a comb belonging to Kahutia-te-rangi, Uenuku rebuked him, pointing out that Kahutia-te-rangi was of high rank while Ruatapu was of low birth (because his mother was a slave wife).
Angry and ashamed at his father's disparaging comments, Ruatapu built a canoe, or waka. When it was finished, he lured Kahutia-te-rangi and a large number of the other sons of Uenuku, all of them young men of high birth, aboard his canoe, and took them out to sea to drown them. He had knocked a hole in the bottom of the canoe, temporarily plugging it with his heel. When far out at sea, he removed his heel, and the canoe sank. Ruatapu then went to each of the young men in turn, and drowned them. However, Kahutia-te-rangi recited an incantation invoking the Southern Right Whale or the Southern Humpback whales (paikea in Māori) to carry him ashore. Kahutia-te-rangi was the sole survivor of his brother's evildoings and assumed the name Paikea as a memorial of the assistance he received from the whales.
The episode where Ruatapu threatens to return as the great waves of the eighth month may explain other accounts which portray Ruatapu as having invoked a great flood. Such accounts or conclusions may result from Christian influence. According to Ruatapu's account in the Ngāti Porou accounts translated by Reedy (1993, 1997), Ruatapu shouted out to Kahutia-te-rangi that he would return to fight him: "The great waves of the eighth month, they are me! I am then approaching!" In an endnote, Reedy writes:
In the eighth month of the Māori calendar, in the early summer, large waves known as ngā tai o Rangawhenua, Rangawhenua's waves, sometimes break upon the shore on the East Coast. In this episode Ruatapu announces that in the eighth month he will take this form, and follow Paikea.