And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.(Genesis 1:2) KJV
A word that ties together a developing theory for the interior of the Earth is tehom, the deep. The deep is first mentioned in Genesis 1:2 as a body of water which predates creation.
When he prepared the heavens, I was there: when he set a compass upon the face of the depth:(Proverbs 8:27) KJV
As the Earth is created, on the second day the depth is divided into waters above and waters below the firmament. We have gone to great lengths to develop this doctrine in the month of February.
He gathereth the waters of the sea together as an heap: he layeth up the depth in storehouses.(Psalms 33:7) KJV
On the third day the waters below the firmament are enclosed within the Earth in a process similar to how the potter’s hand takes a solid lump of clay and makes it into a hollow vessel. At this time the depth or the deep begins to be referred to as the depths or the great deep. They are all ways that tehom has been rendered. The great deep is now inside the Earth.