By bathing in a river on the island of Grand Havai'i, young Terehe defied a prohibition. The angry gods brought up an eel from the depths. Agitated, it then devoured a piece of land, causing the separation of the great Havai'i and the birth of Raiatea and Taha'a. The eel, which has become the Tahiti Nui fish, is then taken to another destination and becomes an island.
In very ancient times, Raiatea and Taha'a formed one big island called the big Havai'i. One day on this island, the priests undertake the construction of a new marae and proclaim a tapu (a prohibition). No noise should be made so as not to disturb the sacred atmosphere. No rooster should crow. No dog should bark. No one should move.
But a young girl from the royal family of Raiatea, Terehe, of rare beauty, breaks the sacred law and bathes in the river. The irritated gods bring out of a hole a tunapu, an eel of the depths, which swallows Terehe in one fell swoop.
But the soul of Terehe disturbs the spirit of the eel which descends into the depths. Losing its balance, the eel swims in all directions, leaps around, tearing up trees and rocks. She devours the middle of the island. A strait is thus born which separates the great Havai'i into two distinct islands: Raiatea and Taha'a. The eel grows bigger and bigger and in turn turns into a huge fish. The god Taaroa then sends the high priest Turahunui to guide the fish to its destination.
The fish takes the name of Tahiti Nui (the big Tahiti). Arrived at the destination, at the time of stabilizing the fish, no warrior is able to free it with his ax despite their courage and valor. One then appeals to Tafa'i-upo'o-tu, the worthy-hearted hero who proposes to go to Tubuai seek the Sacred Ax from High Chief Marere Nui.
Tafa'i returns with the ax of supernatural power but it is so heavy that he cannot lift it. Tafa'i summons Tinorua, the master of the ocean. The ax then becomes light and he can easily break the bonds of the gigantic fish, which has become an island.
This big and beautiful fish has become the beautiful island of Tahiti. 'Orohena, the highest mountain, is as its name suggests, the first dorsal fin. Tahiti iti (little Tahiti, the peninsula) and Moorea were the second dorsal fin. The islands of Me'etia (Mehetia) and Teti'aroa are droppings from the fish when it stopped at Hitia'a.