Ok so I just left Cosmo Canyon on the second disk after leaving the huge materia in the wierd space room. Anyways, I can't figure out what to do now. I looked on a guide and it says to get my submarine but I failed the submarine mission and went on, can I still have access to it? Also, how was a person supposed to know they needed a submarine and where to go if they don't look on a guide, was there something in the game that I missed?