The Oxford English Dictionary defines 'ISLOMANIA' as: A passion or craze for islands

The word is used by Lawrence Durrell in his book 'Reflections on a Marine Venus'. This work, first published in 1953, is Durrell's account of two years spent on the island of Rhodes.
Here follows the opening pasage from his book:
Somewhere among the note-books of Gideon I once found a list of diseases as yet unclassified by medical science, and among these there occurred the word Islomania, which was described as a rare but by no means unknown affliction of spirit. There are people, Gideon used to say, by way of explanation, who find islands somehow irresistible. The mere knowledge that they are on an island, a little world surrounded by the sea, fells them with an in-describable intoxication. These born 'islomanes', he used to add, are the direct descendants of the Atlanteans, and it is towards the lost Atlantis that their subconscious yearns throughout their island life.