I'm beginning to think that Labrynna and Holodrum might be in the same general location as
OoT Hyrule was. Before I begin, though, I'd like to state my opinion that
TWW Link went off to find New Hyrule that would one day become
TMC Hyrule and
ALttP Hyrule.
Now I believe that the Oracle girls are Human embodiments of the Godesses. Din the girl has the power to shape the earth. Nayru the girl has the power to contol time, and I believe the Godess of Time from
MM is Nayru the Godess. Farore the girl knows the secrets of both lands, and she keeps them in her book. These secrets are directly related to the people, and Farore the Godess created life in Hyrule. Farore the Godess can also teleport.
Also of importance is that Kotate and Koume are there, and want to revive Ganon in Holodrum or Labrynna instead of Hyrule. If you believe that there could be more than one Ganon, then this could be the same Ganon from
TWW, while Ganon from
FSA could be another.
Let's go back to the Deku Tree's idea of planting trees to drain the water. plant growth above sea level could have created many catacombs that could now be Subrosia. I have no idea why it would be so hot down there though.
The Godesses could be trying to restore Old Hyrule to its former glory after flooding the place through the Oacle girls that have power over the lands. That's my theory, and I hope it doesn't have too many holes.