When you have control of the airship (After going to Zanarkand) you will be able to go anywhere in Spira. But there are also places that arent put in yet. Go to the airship screen and select input.
Password 1-GODHAND
This gives you access to the ravine below mushroom rock road. You can also get Rikku's ultimate weapon there.
Password 2-VICTORIOUS
This gives you access to some ruins in Besaid where you can get Rikku's armour, Victorious.
Password 3-MURASAME
This one gives you access to another Besaid ruin. You can also find Auron's weapon Murasame.
Also there are places which you can only find by looking for them on the coordinates screen.
Baaj Temple-X=11-16 Y=57-63
Sanubia Desert-X=12-16 Y=41-45
Besaid falls-X=29-32 Y=73-76
Mi'hen Ruins-X=33-36 Y=55-60
Battle site-X=39-43 Y=55-60
Omega Ruins-X=69-75 Y=33-38.
