Can you get to Ultimate wepion on the 3rd disk or dose it have to be on the 4th? I've never tryed to fight it on the 3rd disk so I was just woundering.

Third disc is just fine.

yuppers, 3rd disc. I had to think for a while before I could even remember ultimate weapon. i really need to hit that game again

I just bet Bahamut and went back in afterwards and those roots wernt there (the ones you climb down). How long do I have to wait for that to happen?

Try putting Zell in your party, or screwing about on the airship a bit...

Zell is helpful, although you have to battle craploads of monsters if he's in your team. The monsters are harder than Ultima Weapon!! Go to the airship, have some conference or something, then you can go in the hole and kill Ultima Weapon.

I just bet Bahamut and went back in afterwards and those roots wernt there (the ones you climb down). How long do I have to wait for that to happen? You need to exit the Deep Sea Research Centre completely, meaning go back on your airship, and then land there again. The path will now be open for you to go further. Be sure to take Zell at least until you get to the second save point of the Centre, or else you're just wasting your time. When you get to the last screen (where you take on Ultima Weapon), enable Siren's Move-Find to find another (very valuable) save point.

Good luck.

Not true --- you can do all the RSP stuff just fine without Zell. I just thought having him in your party helped to get the entrance to show up, but I guess not.