[Originally posted at Slacktivist.]
In my largely stolen from Dante cosmology for the series of stories I mentioned before I decided that is Hell was located in what was basically the spiritual/astral/whatever plane associated with Earth (the reason you can't see angels or demons when they don't want to be seen is that they're standing on the spirit side of things*) the metaphysical plane and the physical one looked pretty much the same until Satan was smashed into the metaphysical one causing the changes cited in Dante. (Looked the same on the surface I mean, inside the workings would be entirely different thus allowing Hell to exist as described.)
This somewhat complicates escaping Hell by climbing down Satan's back and up Purgatory and stealing fruit of the tree of life to revive yourself because ideally you'd want to make the transition in a place where you were standing on dry land and the topography of both planes at least somewhat matched.
It might be worth noting that if Dante were right then it looks like Purgatory would be in the middle of the pacific ocean.
* Like Daniel Jackson/Sam Carter/Whoever it was this week when they're shuffled somewhat sideways such that they're invisible and can pass through solid objects.