Rabbi Elazar said: At the beginning of the creation of the world, the Holy One blessed be He decreed: “Let the water…be gathered.” Why [is it written:] “He calls the water of the sea” (Amos 5:8), “He calls the water of the sea” (Amos 9:6) twice? Once for the generation of the Flood and once for the generation of Enosh.4The implied question is: Since God decreed at creation that the waters should be limited to one place, how is it that they subsequently came back and covered the earth? (see Devarim Rabba 10:2).
It is because: “God acted so they would be in fear of Him” (Ecclesiastes 3:14). This is analogous to a province that rebelled against the king. The king sent a powerful legion and surrounded it so that the residents of the province would see it and be in fear of him. So, why is it that: “He heaps together the water of the sea”? (Psalms 33:7).
It is so “the entire earth would be in fear of the Lord…” (Psalms 33:8).5The water was gathered together into one place so that men would see it and be in fear that it may come back and cover them.