Where can I find the "Underwater" Materia in Final fantaisie VII?

Go to Junon and start traveling to the underwater reactor. Once toi are on the long underwater path before toi actually enter the reactor toi will get in somewhat frequent battles with a large bateau with a skeleton on the front and it performs an eject déplacer with it's paddle. Morph it and toi get a book of some sort can't remember the exact name.

Then toi take that book to Kalm and in the, kinda haut, retour au début right corner there is a house. Go in that house then go up stairs and there will be a guy there. Give him the book, he gives toi the underwater materia. (also give this guy the rose obtained from beating ruby weapon and toi get a or chocobo but par that time I definitely have one]