The Biblical story of the great flood represents two or more different flood story traditions, combined and interwoven, seen in the various internal conflicts, confusing narrative, and the inclusion of anachronistic material, such as laws and cultural ideas from much later in the development of the Hebrew culture.
The story as presented in Genesis 6-9 may be outlined as follows: God or YHWH saw that creation was corrupt, sinful. He therefore decided to destroy all living creatures. However, one man, Noah, found favour with God, because of his righteousness; God decided to save Noah and his wife, along with their three sons and their wives. God instructed Noah in the building of an ark to detailed specifications. God also commanded Noah to bring along a male and female of every kind of animal, though later in the story, Noah is told to bring seven pairs of each kind of clean animal, and one pair each of the unclean ones, introducing an obvious anachronism, as the Hebrew dietary restrictions did not yet exist, and until near the end of the flood story, humanity was vegetarian.
The flood came, caused by forty days and forty nights of rain, assisted by the opening of the earth’s springs. The narrative conflicts on how long the flood lasted, giving one account of fifty-four days (forty days plus two weeks) and another, interwoven with the other account, which gives a considerably longer period of one year and ten days.
After the rain stops, the ark eventually comes to rest on a mountain. Noah releases a raven, which continued to fly indefinitely until the waters dried up sufficiently, and did not return. Then Noah releases a dove. The first time, it returned after having found no perch, the second time returning with an olive leaf, indicating that there was dry land, and the third time it did not return, indicating that the flood had receded.
God then releases Noah and his family members along with the animals that had been on the ark, commanding them to go forth and multiply, an echo of the creation story. A few verses later, Noah is described as building an altar and gathering the clean animals in order to make a burnt sacrifice, the smell of which is so pleasing to God that God decides “in his heart” never again to destroy all living things on account of humanity.
Later, in what appears a different narrative voice, God repeats the command to be fruitful and multiply, adds a few more proclamations giving humankind dominion over animals and allowing humans to use animals for food, sets up some other rules of conduct, reiterates the procreation command, and establishes a formal covenant with humankind (rather than just deciding “in his heart”), and places the rainbow as a sign of the covenant. God, although acknowledging that humans are naturally inclined to do evil, has formed the beginning of a new relationship with humanity, based on humanity obeying God’s will in exchange for protection and providence.
The flood myth probably originated in Mesopotamia, predating the Biblical story. In the Mesopotamian version, the flood is brought about because of overpopulation, humanity making so much noise that it disturbs the gods. One man is saved, Atrahasis or Utnapishtim, along with his wife, due to his own wisdom and the favour of the god, Ea, who warned him in advance to build a boat, which he does, and brings along pairs of animals to repopulate the earth. The flood lasts for six days and seven nights, and the test made to see if the waters had receded was to send forth a dove, which returned, then a swallow, which returned, then a raven, which did not return. Then, as in the second narrative voice in the Biblical account, a sacrifice is made, the smell of which pleases the gods, who respond by bestowing a blessing upon Utnapishtim and his wife, making them as gods, rewarding humanity for having saved the animals and humankind through wisdom and cleverness.
The parallels between the Mesopotamian and Biblical myths are striking, including the anger of the gods, a man who escapes the destruction by building a boat, the carrying of animals for re-population, mountains that are covered with water, the sending out of birds to test the waters, grounding of the boat on a mountain as the water recedes, the sacrifice on the mountain, followed by a blessing from the gods.