One secret within “Final Fantasy VII” is the waterfall cave. This area can be found any time after the party obtains the submarine, however if the player wants the rewards that it brings, he or she must venture there before the end of disk 2.
The only two ways to get to this area are via the submarine, or a mountain climbing Chocobo. Once in the submarine, under water a long tunnel area can be found. On the other end of this area is a round clearing, but seemingly a dead-end. However, if the player surfaces in this area, the submarine will be in a lake surrounded by mountains with a small stream flowing down from the area, and a large waterfall pouring in.
There is also a small patch of land for the party to disembark, and when attempting to walk into the waterfall, a cave will be discovered. Inside this cave lies a woman encased in crystal, who is associated with Vincent Valentine and his troubled past. Upon the first visit in disk 2, a cut-scene will play out that tells the player a bit more about the mysterious ex-Turk.
After the dialogue, there is nothing else to do in this area but wander around, and initially might lead people to believe that the zone was simply to learn a hidden story point about the optionally-obtained character Vincent. However, after several real-time hours have passed while playing the game, whether it be by grinding or simply advancing the story, if the player returns to the same location, he or she will receive a mighty reward. Vincent will obtain his final Limit Break, Chaos, and his ultimate weapon, Death Penalty, which grows stronger with the amount of enemies that Vincent lands the killing blow on.