Terebinthia

Terebinthia is a sovereign island-kingdom in the Great Eastern Ocean, the closest island to it being the island of Galma, which is a duchy under the authority of the Kingdom of Narnia. During the voyages of Caspian X a sickness on the island prevented them from going ashore there. Its name originates from the terebinth tree in the Bible.

Trivia

 * The imaginary country of Terabithia from the book "Bridge to Terabithia" is, though subconsciously, derived from the name of this island.