the setting is an unnamed cay deep in the Devil's Mouth, long U-shaped coral banks in the Caribbean. A cay (pronounced "key" is is a small, low island consisting mostly of sand or coral. The word is used almost exclusively in the Caribbean, though it is sometimes used in the context of other tropical environments, such as the Great Barrier Reef and especially in the Florida Keys.
It is a bunch of small islands together which are hard to find by sailors but easy to find if there is a signal fire and your a pilot
in the Caribbean and West Indies