Yerssot, it doesn't matter what would be better. Pure logistics dicatates that that planet HAS to be supplied by others! They have no choice in it.
Tight military control of the supply worlds and the trade routes would be part of any military defence scheme and probably the core of the Galactic Empire to come.
I meant the EMPIRE would have such a tight military control. The Republic probably didn;t, but then it was in decline.
Look, the simple fact is that a completely urbansied planet with natural sources removed) with so many countless billions on cannot POSSIBLY be self-supporting!
Coruscant itself is clearly based on the city world of Trantor, from Isaac Asimov's Foundation series (the two are eerily similar...).
The 20 closest worlds to Trantor had been entitrely dedicated to supplying this unbelievably vast urban jungle of people with what they needed.
What is Isaac Asimov's Foundation series?
Coruscant has to have a ground level, something that the first inhabbitants built on. So it is possible that there is an ocean there. Maybe it's like oil and they have to drill for water.
Or maybe that what all the moisture farmers work for. Who buys the moisture that they farm anyway?
Isaac Asimov's Foundation series was one of the first ever sci-fi franchises (along with his Robot series; he eventually amalgamated the two); it is legendaryt and sci-fi and without his influence much modern day sci-fi would not exist.
After his death (with the story not wuite finished), three sequal books were written, and they were not very good. Greg Bear's one was SO bad that I refused to touch Rogue Planet with a bargepole when it came out.
Don't go overboard on what the book says, Tex, though we have no reason to think it is wrong.
Point is, it's not going to be an ocean in the way which we would recognise it.