Legend of Trentren Vilu and Caicai Vilu

It is said that after Caicai awoke from his years-long slumber, he became enraged because of the ungratefulness that men showed for every gift given to them by the sea, and desired to punish humanity and to incorporate all terrestrial life to his dominions.

Caicai was partially defeated as he was not able to flood all the land; however, the waters did not return completely to their old level, giving Chile its current geography.

[2] According to Chiloé tradition, Caicai was satisfied with the portion of land that he had managed to flood, and delegated his functions pertaining to the sea to the great Millalobo.

According to Mapuche tradition, after the cataclysm, everyone continued their quiet life; until one day it was Trentren who was angered by the attitude that men had, and made all the volcanoes erupt and the population had to move to other safer places.

From that moment on, Trentren continues to manifest itself through earthquakes and volcanic eruptions, while Caicai causes tidal waves and floods when he rolls over during his sleep.

Many variations of the myth exist which can be explained through the vast area the Mapuche culture covers and the fact that many of these stories have been carried through oral tradition.

Some Huilliche communities of Chiloé say that the battle originated because a daughter of the Trauco rejected the pillán Peripillán, and for this reason her son decided to take revenge.

In Argentina there are other later versions of the myth, which change the original parents of both mythical snakes, indicating that they would be brothers and/or sons of the gods Nguenechèn and Kueyen.