"So is this great and wide sea, wherein are things creeping innumerable, both small and great beasts" (Psalm 104:25).
The oceans of the world are indeed great and wide and comprise essentially one sea, in contrast to the Seas of the pre-Flood world (Genesis 1:10), which were probably relatively narrow, numerous and distributed more or less uniformly around the globe, as inferred from the marine fossil deposits laid down in those basins by the Flood. The present oceans, however, now contain the vast reservoirs of water poured out through the fountains of the great deep--all of which were broken up in one day--plus the torrents coming from the windows of heaven, which were opened that same day (Genesis 7:11).
The Flood not only destroyed everything on the land (Genesis 7:22), but also great numbers of marine organisms. After the Flood, however, with the vastly enlarged oceanic environments available, the surviving marine organisms quickly spread and proliferated, so that the oceans now indeed harbor innumerable creeping things as well as both small and great beasts. Some whales, for example, are even larger than the great dinosaurs, which had mostly been drowned and buried in the waters and sediments eroded by the Flood. Even the fearsome Leviathan (possibly something like a giant plesiosaur or sea serpent) plays there (Psalm 104:26). Those men who now "do business in great waters" do indeed "see the works of the Lord, and His wonders in the deep" (Psalm 107:23-24).
In the coming New Earth, however, there will be "no more sea" (Revelation 21:1). All the innumerable sea creatures will be gone as well. There will still be an abundance of water, however. There will be "a pure river of water of life, . . . proceeding out of the throne of God" and "whosoever will, let him take the water of life freely" (Revelation 22:1,17). HMM