Maybe even guard stations or something that won't let you leave? (you are in prison for trying to come in)
id murder every last one.
Natural borders (mountains) and an endless sea.
id keep swimming arround the landmass...i did it in wow all the time..dont ask why.
I just hope it's not invisible walls.
i used to try to glitch through the walls in oblivion, so far no luck. i did fall through the jerall mountains once.