Location Under Gold Saucer
The Corel Prison is located in the exact same spot of the map as Gold Saucer because it is actually just a prison that makes up the base of the “Gold Saucer tree”. The prison doesn’t really have any security or guards, for the most part, and operates in a state of semi-lawlessness.
The story takes you through Corel Prison just one time and then you can no longer return to this location in the game. Check out the Corel Prison walkthrough section for details. You wind up in the Corel Prison after a man with a gun-arm (Dyne) goes on a rampage in Battle Square and your party ends up taking the fall as the guilty person is assumed to have been Barret.
There is one shop that you can find in the pub-style building where you can purchase just a few basic items listed below:
The map below shows the location of the Corel Prison (and Gold Saucer) on the World Map: