Regarding Ophir in Genesis 2:8-12, I have always wondered about this perhaps being a cavern realm location or perhaps an concave location insomuch that in Greek ophis (ὄφις) is snake. We also see words like ophidian or ophites, etc. with the seemingly same root. In Hebrew we get the word "naga" (נחש; transliterated: nachas(h); 'ch' is hard like in German Bach; could call it a mushy "G" sound). Clearly there's no "definite" answer to where or what "Ophir" was/is in current context and current available history.
I do agree with you @Ephraimite regarding there being a plethora of references that are lost to society by either simply not being aware of the concepts of the cavern and hollow/concave Earth or by obfuscation. If we could more carefully read it and other ancient scriptures in their original languages from the authors I suspect we could obtain much greater possession of such references.
@SilverMoon the inner portion of the Earth has a small "sun" (unsure if fusion or fission or some other process; likely as perhaps many/most (?) actual planets have it seems; and it would seem that life is much more abundant in our universe than previously thought given this concept and the shielding that crusts provide) and this probably has some role in all of this melting/transformation/transmutation.
Regarding in and under ground, just the accounts here in this and the cavern worlds subforum can set your mind afire to all of the possibilities. There are FAR too many to otherwise consider otherwise. Michael Mott's book is a little marvel itself: 4th Edition: Caverns, Cauldrons & Concealed Creatures. Mr. Mott has apparently had some (violent) one-on-one encounters with these creatures/beings. Also consider Harry Hubbard's incredible videos: https://www.youtube.com/c/IllinoisCaves/videos - notice the recent photos he's shared in the galleries videos (!!!). So much more can be discussed here and of course 20 years of discussion and sharing in here and in the archive.
And yes, Doctrine & Covenants 133 (D&C 133) is clearly referring to something much, much further beyond what we are familiar with presently. Clearly this is the case with their being a highway "in the midst of the great deep". This could be considered "the abyss" as previously discussed, etc. The ice will melt - this is clearly significant and no small feat / feature of their advent. And no, this is not the laughable "global warming" trash that is being spouted by the Luciferians and the deceived.