The return of the chaos monster?

The significance of the flood story is that it is told as a story of the undoing of Genesis 1, as a move towards de-creation. God is unraveling the separations he had put in place between the waters above and the waters below, and between the land and the sea. The terrifying story of Noah’s flood—and to the ancient mind it really was terrifying—is almost a return to the primeval chaos of Gen 1:2.

And it would have been the end of the world had God not “remembered Noah” and shut up the fountains of the deep and closed the windows of the heavens, promising never to flood the earth again. As a sign of this end to hostility 
God reversed his archer’s bow and extended it away from himself towards 
the earth as a sign of peace. Genesis speaks merely of a “bow” in the sky, but we call this divine archer’s bow a rainbow.— The Biblical Cosmos, page 39