In a tobacco-induced dream, a hunter was told by the daughter of the water spirit Tsunki to return to a river. He did so, met the woman, followed her to her father's house, and became her husband. When he returned to his home on earth, she took the form of a snake. Once while he was off hunting, though, his two earthly wives tormented her, and she returned to her father. Tsunki, in a rage, flooded the earth, drowning everyone but the hunter and one of his daughters, who escaped to a mountaintop. These two repopulated the world. [Bierhorst]
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References: Bierhorst, John. The Mythology of South America, William Morrow, New York, 1988.