Rashi — Genesis 6:17

“ואני הנני מביא AND I, BEHOLD, I DO BRING — God says, “Now I am prepared to agree with those angels who cautioned Me and long ago said to Me (when I was about to create man), (Psalms 8:5) “What is man that thou art mindful of him” (Genesis Rabbah 31:12). מבול A FLOOD — so called because it ruined (בלה) everything; because it cast everything into confusion (בלל), and because it brought (הוביל from root יבל) everything down from the heights to a lower level. And this last explanation underlies the translation of Onkelos who translates it by טופנא (Ar. טוף = Heb. צוף) because the Flood caused everything to float about and brought it (the Ark) to Babel which is a low-lying district. That is the reason why it (Babylon) is called, also, Shinar (שנער): because all those who died through the Flood were shaken out (ננערו) into it (Shabbat 113b).”