Indications are, that this Realm is to be found somewhere in the Brownwater region near to the Aurellis Continuum. and that, unsurprisingly, there is much fire to be found there.
It is also rumoured, but as of yet, unproved, that there may be certain direct links to this Realm, from the middle of certain volcanoes to be found in and around the Outside zone of the Aurellis Continuum.
Princess Tarassin of the 9th Abyss.
Update: We now know exactly where this Abyss Realm is. It’s a volcanic cork, at the bottom of that new Abyss Hole that formed on the former Jesbyways in Thelbane. And it’s totally a Volcano. Nobody is going Abyss diving down there.