Caves of fiction, caves of literature, are simply caves made up to be part of a story. Many books take place partly or completely inside a cave. Some are describing existing caves, and we are happy to list them on our cave pages. But some use invented caves, which may be realistic or even fantastic.
If you ask, what we mean: think about the caves of Jules Verne's A Journey to the Center of the Earth. We found actually the best examples in the book The Lord of the Rings. They are not simply used as the location for the story, they are elaborately described. Other caves are well known but actually never really described, for example the bat cave of Batman. Such a cave is actually a kind of stereotype, more than a fictitious place.
There is another category of such invented caves we called virtual caves, and there is a basic difference between those two. Fictitious caves are part of a fictional story, and as such they are not intended to be recognized as being real. They are not a hoax or bluff, they are simply an important part of a story and actually as fictious as the rest of the story. Virtual caves on the other side are definitely a hoax, they are made up to look as real as possible and are not easily detected as being a hoax.
We are listing numerous fictitious caves on showcaves.com.