Is ther a difference with FF I on GBA??? Well, i don't really know...
But anyways. I remeber that you have to use the ship to get to a port with a Big Castle & a town to the south east, Elfeheim is it's name i think. . There are elves living in it. You'll have to go see the prince of the castle who is kept sleeping because of a wisard. Check this :
http://www.gamefaqs.com/portable/gba...e/920240/35236
It's hard to find where you have to go when on the boat, but don't give up.