If we look around scripture for descriptions of what the world looks like, we can run into some strange and confusing terms pretty quickly: the firmament, pillars of the earth, storehouses of wind, hail, and thunder, the highest heavens. As the world is created, we hear in Genesis 1 that God said, “Let there be a dome in the midst of the waters, and let it separate the waters from the waters.” In some Bibles, this “dome” is translated as the firmament and God calls this dome/firmament the “Sky.” The ancient Israelites thought that there was watery chaos – tehom – and that it contained sea monsters who were enemies of God. Psalm 74 (and other places) tell us that in the work of creation, God conquered the monsters before separating the primal waters above and below the earth.
So the earth was on pillars, elsewhere in the Bible called the “foundation of the earth” over the watery deep. The earth was thought to be flat – an expanse with mountains and other features. Beneath the earth was the underworld; above the earth was heaven where God lived with the heavenly host, also supported by pillars; above that was more watery chaos. This dome that separated the waters from the sky was likely thought to be made of metal, but in Exodus 24, the floor of the throne room of God is said to be of sapphire – explaining why the sky is blue. God’s heaven was thought to be a specific chamber, resting on the dome of the sky. In short, lacking the scientific resources that we have today, they saw a three-story world: heaven above, earth in the middle, and hell below. The picture below expresses this worldview. It depicts a traveler that has traveled so long and so far that he has reached the literal end of the earth. He has found the dome of the firmament and, out of curiosity, he stuck his head through to see what was on the other side.
Resource:
https://en.wikipedia.org/wiki/Biblical_cosmology
Michael Thydell’s colorization (2020) of Where Heaven and Earth Meet from a book by Camille Flammarion, 1888.