Ge 1:9 Then God said, "Let the waters under the heavens be gathered together into one place, and let the dry land appear"; and it was so.

10 And God called the dry land Earth, and the gathering together of the waters He called Seas. And God saw that it was good.

Moses is teaching the Israelites that the gods of the earth and the seas that were worshiped by pagans were false gods. Their God was the one who created the earth and the seas. He is the true God.

The pre-flood earth was like a big island surrounded by bodies of water. The physical division of the earth into continents and islands must have occurred during Noah's Flood.

There were no rivers or lakes. There were only seas. During this time, a mist came out from the earth and watered it.