What do vaults do? They separate and lock, protecting something behind them. And so … there is also water (and more) above us.

And God said, “Let there be a vault between the waters to separate water from water.”

So God made the vault and separated the water under the vault from the water above it. And it was so.

God called the vault “sky.” And there was evening, and there was morning—the second day.

Genesis 1:6-8