Dark World

The Dark World, once the Golden World, is a parallel realm Ganon is imprisoned in after his defeat. The Golden Realm was created by the Goddesses after their creation of Hyrule. The true power of the Triforce can only be unlocked once entrance to the Golden Realm is gained. The only way for one to enter is for a sage or heir of Hyrule, possessing light magic, to open it. When one enters the Golden Realm their true image is shown. The Golden Realm became the Dark Realm when, even though he was imprisoned, Ganon's evil infested this easily susceptible world. Ganon becomes an atrocious monster. Ganon is defeated and sealed many times throughout his reign, and the relative peace is brought to the Dark Realm, or now, the Twilight Realm.

The Dark World, also referred to by such terms as "Evil Realm", "Dark Realm", "World of Evil", and "Underworld", is a dark, twisted realm that serves as Ganon’s territory. While the English version gives it various different titles, the Japanese version has two names for it.

The first and more specific title is “Makai”, literally meaning Demon World. Not to be confused with hell, a Demon World is any territory ruled by a “Maou”, or Demon King. Ganon is the only known Maou in the Zelda series, as his various titles include the word Maou in every game, and no other character has such a title. Thus, in Zelda, a Makai is any territory ruled by Ganon.

The second title is the less specific “Yami no Sekai”, meaning World of Darkness. Much closer to the English translation of Dark World, it is also closer in meaning. A Yami no Sekai is any realm full of darkness. These terms are, however, occasionally used interchangeably in the Zelda series.

The Sacred Realm, apart from a few sections of Hyrule itself, is the only place confirmed to have become Ganon's Dark World in any game, but several games leave its location up to the imagination of the player.

The Legend of Zelda and The Adventure of Link
The original Legend of Zelda makes no direct reference to Ganon's Dark World, but Ganon's title of Maou implies the existence of one. The game speaks about the Underworld, but the Japanese word used here is "chika", which is a literal underground lair, and not specifically a Makai.

The Adventure of Link also talks about the Underworld, but this time, the Japanese word used is Makai. Whether the underground lair of The Legend of Zelda is the Dark World of The Adventure of Link or not is unknown.

A Link to the Past
In A Link to the Past on the Super Nintendo, the Dark World is a corrupted or reversed version of the Golden Land that is created after Ganon reaches it and wishes on the Triforce. It is known that the Golden Land is a mirror that reflects a person's true self, so Ganon and his minions are turned into monsters when they enter the Golden Land, and Link turns into a rabbit unless he has the Moon Pearl. When Ganon takes the Triforce, he wishes to rule the world, and the Triforce grants that wish by turning the Golden Land into his Dark World. When that happens, Hyrule is referred to as the Light World.

The Dark World of A Link to the Past is referred to as a Yami no Sekai, and thus, is not necessarily a Makai. However, Ganon is a Maou in the game, and he clearly has rule over the Dark World, so it matches the description of a Makai.

In the game's ending, Link defeats Ganon and approaches the Triforce. The Triforce tells Link that Ganon's defeat will cause the Dark World to vanish.

Ocarina of Time
In Ocarina of Time, Ganondorf tricks Link into opening up the entrance to the Sacred Realm by opening the Door of Time and pulling the Master Sword from its pedestal. This causes Link to be sealed inside the Chamber of Sages until he is old enough to wield the Master Sword, and allows Ganondorf to enter the Sacred Realm.

As Princess Zelda later tells Link, when Ganondorf entered the Sacred Realm and touched the Triforce, he became an "Evil King", and the Sacred Realm became a "World of Evil". Here, the Japanese version actually calls Ganondorf a Maou, and the World of Evil a Makai. Rauru gives a similar account of the event. However, after Ganondorf transforms into Ganon, and is defeated by Link, Zelda calls for the other Sages to seal him in the corrupted Sacred Realm, and refers to it as the Yami no Sekai. Thus, though the two phrases have different meanings, they are interchangeable to an extent.

Oracle of Seasons and Oracle of Ages
The Dark World is given only a minor mention in the Game Boy Color game Oracle of Seasons, when the main antagonist, Onox, reveals that he was summoned from the Dark Realm by none other than Twinrova .As with A Link to the Past, the term used here is Yami no Sekai.

Oracle of Ages' English translation states that Veran has extended the reach of the Dark Realm, however, that was a mistranslation. The term used there is not "Yami no Sekai", but conversely, "Sekai no Yami". Thus, Veran only extended the "darkness of the world", and not the actual Dark World.

Four Swords Adventures
The Dark World exists in two different forms in Four Swords Adventures. The first is a tainted, parallel world to Hyrule, and the second is its extension into Hyrule.

Though its parallel existence to Hyrule is similar to the Dark World of A Link to the Past, the two differ in several ways. The Dark World of Four Swords Adventures is accessed by Moon Gates, most of which need to be activated by Moon Pearls, whereas in A Link to the Past, the Dark World is accessed by blue portals, and can only be exited by the use of the Magic Mirror, an item absent from Four Swords Adventures. Moon Pearls are used in both, but for different purposes.

The second form of the Dark World is the fifth level in Four Swords Adventures. It consists of three stages: The Lost Woods, Kakariko Village, and Temple of Darkness. It is named so, because it has become completely overcome by darkness.

At the end of each stage is a barrier that can be broken if the four Links have obtained a certain amount of Force Gems. These barriers drain the Force from Hyrule, and if not destroyed, they would eventually transform all of Hyrule into the Dark World, because they are connected to it.

Both forms of the Dark World in Four Swords Adventures are referred to as Makai and Yami no Sekai interchangeablly.

Twilight Princess
The Twilight Realm is never referred to as a Makai or a Yami no Sekai though, so its potential status as a Ganon's Dark World is unconfirmed.

It is debated between fans of whether or not the Dark World is the Twilight Realm (due to similarities in the animal form transformations that Link has in Link to the Past and Twilight Princess. Through information given in Twilight Princess, it can be established that the Twilight Realm and Dark World are two different places in the Zelda Universe.  The case can be made due to the fact that the Twili reside there after being banished by the Sages because of their attempt to claim the Triforce.  Since the Dark World was the Sacred Realm under Ganon, the Twilight Realm would have to be separate from the Dark World.  The Triforce resided in the Sacred Realm and later in the Dark World with Ganon.  The Sages would not have banished the Twili (Dark Interlopers) to a place where they would be present eternally with an object that were attempting to steal.

This concludes that the Dark World and Twilight Realm are two separate places.