Midrash su Salmi 104:7

At Thy rebuke they fled (ibid.). When a man sees that his winepress is filled with grapes, and that his vineyard is ready for cutting, others may ask him: “What will you do with these grapes, since the vat is too small to contain them?” What does he do? He treads down the grapes in the vat and then puts in the new grapes. Then it is able to contain all his grapes. Similarly, though the entire world was submerged under water, the Holy One, blessed be He, declared: Let the dry earth appear (Gen. 1:9). The water thereupon cried out: “Though we fill the entire world, it is cramped for us. Whither shall we go?” What did the Holy One, blessed be He, do? He trampled upon the ocean⁴Normally the Mediterranean, but in this instance, as indicated a few lines below, the Dead Sea. and slew its prince,⁵See Ginzberg, Legends of the Jews 5:26, Bava Batra 74b Leviathan was a legendary sea animal destined to be eaten by the righteous in the future. as it is said: He stirreth up the sea with His power, and by His understanding he smiteth through Rahab (Job 26:12). Smiteth is an expression that indicates slaying, as it is said: And with the hammer she smote Sisera, she smote through his head, yea, she pierced and struck through his temple (Judg. 5:26). The seas mourn (bohin) to this very day because He slew the prince of the sea, as is said: Hast thou entered into the springs (nibhe) of the sea? (Job 38:16). Why did He slay him? Because a house that can accommodate a hundred living people can contain a thousand dead. That is why the ocean is called the Dead Sea. Ultimately, however, the Holy One, blessed be He, will heal it, as it is said: When they shall enter into the sea of the putrid waters, the waters shall be healed (Ezek. 47:8). When the other waters observed that the Holy One, blessed be He, had trampled upon the ocean, they fled from the loud cries of their fellow-waters, as it is said: At Thy rebuke they fled, at the voice of Thy thunder they hastened away (Ps. 104:7).

The waters now are not just jostling for high position. They are crying like a family being torn apart. The lower waters long to go up in order to be reunited with their other half.

THE GATHERING OF THE WATERS
ON the third day all the earth was flat like a plain and the waters covered the surface of all the earth. When the word of the Almighty was uttered, "Let the waters be gathered together" (Gen. 1:9), the mountains and hills arose from the ends of the earth and they were scattered over the surface of all the earth, and valleys were formed over the inner parts of the earth; and the waters were rolled together and gathered into the valleys, as it is said, "And the gathering together of the waters he called seas" (Gen. 1:10). Forthwith the waters became proud and they arose to cover the earth as at first, when the Holy One, blessed be He, rebuked them || and subdued them, and placed them beneath the soles of His feet, and measured them with the hollow of His hand that they should neither decrease nor increase. He made the sand as the boundary of the sea, just like a man who makes a fence for his vineyard. When they rise and see the sand before them they return to their former place, as it is said, "Fear ye not me? saith the Lord: will ye not tremble at my presence, which have placed the sand for the bound of the sea?" (Jer. 5:22).