Saint X is a fictional Caribbean island based on Schaitkin’s research on existing Caribbean islands. The Caribbean includes any islands within the Caribbean Sea, and as such, includes 13 different sovereign island nations, including the Bahamas, Jamaica, Grenada, the Dominican Republic, and the Cayman Islands. Cuba, off the coast of Florida, is the largest island in the Caribbean and the closest to the continental US, and the Caribbean archipelago stretches east and then curves southward from there. The characters who live on Saint X often talk about dreams of moving to either New York City or London, both of which are thousands of miles from where Saint X is said to be.

In the opening of the first chapter, Saint X is situated among real islands that make up the archipelago of the Caribbean Sea, such as Saint Kitts and Saint Vincent. Saint X is in the middle of this archipelago and is 40 kilometers long and 12 kilometers wide. The native vegetation and terrain matches that of the surrounding islands: arid soil, salt ponds, a volcano, and tropical vegetation.

Once Clive Richardson moves from Saint X to New York City, he references the “islandness” of each place, expressing his longing for his home.