Crashed Celnika
Monsters: Unknown 2, Unknown, Serpent, Unknown 3
Items:
Heaven's Cloud, Escort Guard, Conformer, "Double Cut" Materia, Megalixir (x2), Spirit Lance, Outsider, Highwind, "Hades" Materia
Warning:
Be Careful when approaching the Gelnika. The emerald WEAPON is somethims in front of the Gelnika. If the Emerald WEAPON is there, resureface and dive again - it should have moved on.
The Gelnika is a very dangerous place, so make sure you save upon entering the ship. There are no monsters in the entrace area, but the rest of the ship is crawling with all kinds of bizarre creatures.
As you first enter, take the first door on Cloud's right, which is the generator room. Most of the items in this room are on the lower floor, some of which are hidden. Don't miss the Conformer or the "Double Cut" Materia.
In the hall before the cargo bay, the team may bump into Reno and Rude of the Turks, depending on when you do this quest. If you've already had your final battle with the Turks while stopping the Sister Ray, then Reno and Rude won't be around. Otherwise, a fight will ensue.
The cargo bay has two more "must-have" items. One is Cid's Highwind Limit Break and the other is the "Hades" Materia. It's a long walk to both items and Shinra's freakish beasts are out for blood.
You may want to save before leaving the Gelnika. If Emerald WEAPON is sitting in front of the Gelnika when you exit, you might accidentally initiate combat.