Bottom of the Sea

The Bottom of the Sea is a World Map in Final Fantasy VII. The area can only be accessed on Disk 2 when the player obtains a Shinra Sub after the Huge Materia mission at the Underwater Reactor beneath Junon. The main accessible areas of the Bottom of the Sea are in between the center of the three main continents. Most of the locations in the Bottom of the Sea are entirely optional, however the player must enter it for the Key to Ancients to use in the Forgotten City.

As soon as the player can access the underwater areas, Emerald Weapon will be available to fight. Emerald Weapon often circulates the open area of the Bottom of the Sea near Junon, but it also can be found waiting in front of certain locations such as above the underwater crater or in front of the Sunken Gelnika, however surfacing and re-submerging will set it to something else. Emerald Weapon moves faster than the Submarine and therefore surfacing may be easier than trying to move out the way if it is close.

Locations
There is a crater underwater. It is possible it was formed when Sapphire Weapon was defeated, or when Emerald Weapon landed underwater, much like the location where Ultimate Weapon is found near Junon created a massive crater.

The Junon Underwater Reactor can be seen underwater but not accessed.

If the enemy submarine was shot down in the minigame, visiting the sunken submarine south-west from Junon at the Bottom of the Sea will grant the player one of the four Huge Materia items.

The Sunken Gelnika is an optional dungeon underwater. It appears underwater without the player having to watch the FMV at the Airport in Junon, and the player can still watch the FMV showing the Gelnika's take-off even after the player has visited it. To find the Gelnika the submarine must be directed west of Junon and through a gap. Many of the game's rare items can be found here, including the Highwind manual for Cid's final Limit Break, and the Conformer, Yuffie's ultimate weapon. It is also home to many of the game's toughest enemies.

The Key to Ancients is located in the Bottom of the Sea in an underwater tunnel by the Icicle Area. If the player goes to the Forgotten City with Bugenhagen before retrieving the item, they will find the text "……(even sunlight can't reach)……(Key)" written in chalk beneath Ancients' writing. Although it is part of a riddle, Bugenhagen gives hints and basically tells the player the Key to Ancients can be found underwater.

The player can access a location called ??? through the submarine. If the player travels to the top of the eastern continent, and then travels beneath the continent they can go through a series of tunnels and submerge by a waterfall. The player can dock the submarine here and enter a cave behind the waterfall. This cave is important to get the Chaos manual and the Death Penalty weapon, Vincent's final Limit Break and ultimate weapon respectively. The cave can also be accessed with a number of varieties of Chocobo, but not the Highwind.

Enemies
While there are no random encounters underwater, Emerald Weapon appears underwater and will be fought if collided with in the Submarine. The player fights Emerald Weapon underwater with a time limit of twenty minutes to simulate the inability to breathe underwater. The player can receive an Underwater Materia which will remove the time limit by trading a Guide Book item with the Kalm Traveler.

Trivia

 * Since the area visitable by the Submarine underwater is limited, there have been a number of rumors about how to access other areas of the World Map underwater. One rumor is that the player would have to breed a silver chocobo which could go underwater, although this is not possible. One rumor surrounding this was that if the player traveled to North Crater while underwater they could fight the boss Alpha-Leviathan. Since this is not possible, and the enemy doesn't appear within the game files, this is also not true.
 * While the player cannot access certain areas of the World Map underwater, in some places there are still other areas underwater inaccessible by normal means. Much of the main traversible area is replicated, including at the top of the map which cuts off where the top of the World Map is. These areas can only be accessed through hacking the game.
 * Since the player cannot go onto the menu when submerged, the underwater area is never given a specific name. However, if water is turned off on the World Map via a cheat device, the player can run down into the canyons where the ocean is meant to be. Accessing the menu from this position will reveal the area's name is "Bottom of the Sea".