The Location of Dream Zanarkand

[Firo Volondé]

the only person that went to the DZ from Spira was auron. and well he's unsent so dose that have anything to do with going back and forth?

That has everything to do with it, Auron implies shortly after revealing to Tidus that he is unsent that it was only because he died that he could travel to DZ, possibly because unsents have immunity to the toxin. Also, citizens of DZ seem to be able to use Sin as a ferry as well. I would say anyone else who tried that stunt would be badly affected by the toxin or killed by Sin's gravity attack.

Sorry to drag the discussion back, but I'm not convinced by the explanations for DZ people not leaving.

I've wondered this for a little while, but if the people of DZ have their own will to do what they want (which we can clearly see in the game), then why have they never tried to leave their island?

Why do fish stay in the water? It doesn't occur to them to do otherwise. Even with free will, their island is the border of their world. It never occurs to them to leave, it doesn't occur to them that there is anything beyond there. They have their world, and their thoughts are tied to that world.

Look at it this way: most of the time when you dream you aren't aware that you're dreaming. You simply accept the reality and boundaries of the dream without question.

People are not fish and as for dreams the DZ people believe theirs is real so its no different to real life. Jecht did leave and people did notice (Tidus memories show this), even if they mistakenly thought he died.

I think a nearer comparison than the Matrix is the Truman Show.
For a while you can fool people not to leave the "bubble" they are in, but not for ever, and not for 1000 years.

Yevon could have made the citizens of DZ any way he wanted, since he was their creator. Obviously, if they believed they were in the real Zanarkand, they would leave DZ to search for Bevelle, and be too difficult to control while maintaining Sin. His only goal was to keep DZ alive forever; this would be easiest if the citizens didn't wonder about the outside world.

I think (I haven't seen it in ages) that Truman needed a trigger to consider leaving the bubble. That trigger was a workroader he met never met saying "Goodbye Truman". However, Tidus knows that Auron is not a native of DZ, but since he's content to spend the rest of his life in Zanarkand, the trigger obviously has no effect on people in DZ. If the creators of The Truman Show (the show within the movie, not the movie) had been able to mould Truman the way YY moulds the citizens of DZ, he never would have questioned his universe.