This is genuine science fiction from 1864. It is a straight-forward read about a man who's uncle, an eminent Professor of mineralogy, discovers a secret manuscript detailing the entrance to a passage leading to the centre of the Earth, written three hundred years before by a man who claims to have been there and returned. The nephew, reluctant and fearful, is dragged along on an expedition to re-discover the route - if it really exists.
Perhaps a little too much time is spent getting to the subterranean adventures, perhaps not enough time detailing them, but the book is too short for me to ever get truely bored - brevity is a virtue to be aspired to when novel writing, in my view. It may be that the description of a journey from Germany to Iceland would seem exotic and interesting to his audience, few of whom would know much about that northern island. What is certain is that Verne was fully aware of the state of Geology in his time, though it is not clear to me how plausible or otherwise his speculations about the structure of the world below the surface we live on would have been to a contemporary readership. It took another hundred years to complete a self-consistent and convincing theory of the complete structure of the Earth, ruling out Verne's speculations categorically. Such is the way of science-fiction; writers speculate based on the knowledge of the day. Sometimes they are prophetic, more often they are wrong, but the best of them are entertaining and worthwhile regardless - even more than 140 years later!