Isle of Fire

Description
The Isle of Fire is a desolate place, famous for housing the diabolical daemon-machine Exodus. A rocky and inhospitable place, the isle has risen from the Great Sea twice in Britannian history: the first when Exodus first began his campaign of vengeance against ancient Sosaria, and the second when the mage Erethian lifted it from the sea in the course of studying the hellspawn's Dark Core. Although this place has been long stained with the infamy of evil, Lord British nevertheless attempted to bring something of the virtues to this lonely place, establishing three great Shrines to the Principles upon it.

The island, itself, is dominated by the Castle of Fire, at times known as simple as Castle "Death." This dark fortress once served as Exodus' stronghold, and daemons and other servitors of darkness long patrolled its hallways. It is here that the daemon-machine met its end and also here that British's Shrines were established, making the keep the focal point of the isle

Age of Darkness
The Isle of Fire first arose some twenty years after the death of Minax, coming into existence after Exodus had finally finished the course of its observations regarding the world. From its fortress, Castle Death, the daemon-construct rallied armies of monsters to plague the realm of Sosaria, its power waxing so great that it was able to wrest the Great Earth Serpent from the Void itself and install it as the island's guardian. Desperate to understand the evil which was festering in the Great Sea, Lord British sent Shamino to investigate the Isle of Fire and its Keep, only to have his friend return to him overwhelmed with madness, his mind having been broken by what he'd seen.

Eventually, the Stranger and their companions were able to battle their way to the isle, passing the great serpent and entering the castle, where the Exotic Armour kept them safe from the fires which burned there. After tricking the machine into its own destruction, the heroes fled the dark fortress, never speaking again of what befell them there.

Age of Enlightenment
In the years that followed, Lord British endeavored to cast aside the barbarity which had marked the Age of Darkness and to usher in a new era of enlightened learning and virtuous piety. Eager to establish some seed of righteousness in this place of abomination, Lord British ordered the construction of great shrines to the Principles of Love, Truth and Courage on the Isle of Fire, hoping that someday a champion of the virtues might find it a testing-ground for their mettle. Before such quests could be embarked upon, however, the isle sank into the sea - and event likely triggered by the then unknown Gargoyles, who had channeled Exodus' psyche from the Void and bound it to their own Shrine of Diligence on the out side of the world.

Age of Armageddon
The island and its castle remained under the sea for hundreds of years, yet during this time it was not closed to all who would explore it. Mages of great power, such as Erethian, Castambre, and Astelleron made their way to its shores, with the latter establishing a great air bubble around the isle, that mortals may survive there. Eventually, it was Erethian who uncovered the means to force the island to rise once again to the surface, having gleaned such knowledge from the Dark Core of Exodus which still remained there.

The Avatar, now able to seek out the shrines established for their use so long ago, journeyed to the island at British's behalf. Solving the tests that still lay active on the islands shores, the hero eventually managed to banish the Dark Core into the Void that Exodus's resurrection might be averted - a move that drove the enraged Erethian to provoke his own death. While the isle still stood for some time after this final victory over evil machine, it was not present during the Avatar's last journeys in the ream following the Great Cataclysm, presumably having sunken into the deep once again.

Ultima III

 * Exodus
 * The Great Earth Serpent

Ultima VII

 * Adjhar
 * Arcadion
 * Bollux
 * Dracothraxus
 * Erethian
 * Exodus's Dark Core

Trivia

 * In the Nintendo port of Ultima III, the Isle of Fire begins to sink immediately after the death of Exodus, and the final moments of game play involve controlling the party as the flee the crumbling castle.
 * In the Seiji Tanaka's manga,  Ultima: The Terror of Exodus, Exodus' stronghold has a twisted Lovecraftian appearance, which showcases the machine-like qualities of both the daemon and its stronghold.