The 15th century phantom island known as Antillia was supposed to exist in which ocean?

Tales of islands found in the Atlantic Ocean, both in fact and legend date back as far as stories by Plato concerning Atlantis and Roman author Pliny the Elder writing about the Canary Islands. The story about the island called Antillia dates back to the Muslim conquest of Iberia (present-day Spain and Portugal, also referred to as Hispania). The legend states about 714 AD, seven bishops with their parishioners sail westward from Iberia into the Atlantic Ocean to escape the Arab invaders. Seven cities were said to have been established on this relatively large island.

The legend is found inscribed on maps made during the 15th and early 16th centuries. The map made by cartographer Johannes Ruysch dated to 1507-1508, shows Antillia prominently in the Atlantic with a written mention of the legend. An excerpt from the map translated into English: "This island Antilia was once found by the Portuguese, but now when it is searched, cannot be found. People found here speak the Hispanic language, and are believed to have fled here in face of a barbarian invasion of Hispania."

The term phantom island refers to a purported island that appears on maps for a period of time but was removed in later maps after it was proven not to exist. Later maps and globes, particularly after Spain's discovery of South America, Antillia shrinks in size and is either removed or in some cases incorporated within the Azores.