@deandddd Amazing findings there. Other terms to search the scriptures for might be "under the earth", "in the earth", "bowels of the earth", etc. I think it's significant to note that when the Bible talks about "the ends of the earth," it's talking about the North and South Poles (in my opinion). There are many other veiled references to underground realms and hollow earth littered throughout the Bible.
Also, you may be interested in my somewhat-related topic here: Abinadi condemns worship of underground creatures
To any Latter-day Saints out there, also keep an eye out whenever the scriptures talk about "northern countries." When you go really far north, where do you end up? Inside the earth... just like the legends of Ultima Thule, Hyperborea, etc. (where do you think the lost ten tribes are?)