Ruatapu was a son of the great chief Uenuku, and a master canoeist in Polynesian tradition who is said to have lived around 30 generations ago. Most Māori stories agree he was an older half-brother of Paikea and 69 other sons, while traditions recorded from the Cook Islands sometimes state he was Uanuku Rakeiora's only son.
In the oral traditions of the Cook Islands, Ruatapu travels around central Polynesia; from the Society Islands, to the Cook Islands, and lastly to Tonga before coming back to the Cook Islands to live out the rest of his days and eventually die at Aitutaki. Most traditions record him as a prominent ancestor, gaining three wives between the last two groups of islands.
Cook Island traditions
The stories relating to Ruatapu's life are fairly consistent with each other. The Journal of the Polynesian Society records at least two variations given from Aitutaki recorded from historian Timi Koro, and Chief Isaia, and Chief Tararo of Ma'uke, translated by Major J.T. Large at Mangaia. According to a native of Atiu, there is also a tribe known as Ruatapu.
Ruatapu's travels
Ruatapu and his father Chief Uanuku Rakeiora lived at Taputapuatea on Ra'iātea some 30 or so generations ago, and were descendants of Iro-nui-ma Oata.
Another telling says that Ruatapu used Uenuku's own hairpiece, believing himself to be the senior son, as the eldest, when in fact Kahutiaterangi was the senior son owing to a difference in lineage. Ruatapu then went away and built his own large canoe that could hold 140 people. Once finished he announced that he would set off in it, and then killed everyone aboard with a spear, save for Paikea, who took to the ocean and was saved by the gods.
In yet another telling says that Chief Uenuku made a canoe for the nobility and was preparing the hair of all 70 of his noble children for their first sail inside of it. Uenuku himself, combed, oiled, and tied the hair of every last one of them, except Ruatapu. When Ruatapu asked why his father had not treated his hair, Uenuku told him he could not because he was the only son of a slave woman, and his hair was not tapu like his brothers'. This put Ruatapu to shame, and so he refused to eat dinner that night, instead going down to the canoe and putting a hole in its bottom, before filling it with wood chips and hiding the canoe's bailer. In the morning when they launched the canoe, Ruatapu hid the hole with his heel. When they were far out at sea he released the hole and removed the chips. The water rushed in, and nobody could find the bailer as Ruatapu had hidden it onshore. Everybody drowned, except Paikea, who was saved through his mother's ancestor Tangaroa who summoned the whale. Ruatapu's last attempt at killing Paikea was to use an incantation to hurl waves at him. This backfired as Paikea was too far away now, and the waves just rolled back onto Ruatapu thus drowning him.
Ngāti Porou tradition
In a tradition of Ngāti Porou, Ruatapu became angry when his father Uenuku elevated his younger half-brother Kahutiaterangi ahead of him in status. Ruatapu lured Kahutiaterangi and a large number of young men of high birth into his canoe, and took them out to sea where he drowned them. He called on the gods to destroy his enemies and threatened to return as the great waves of early summer, shouting out to Kahutiaterangi 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:
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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.