As Axel Lidenbrock, his uncle Otto, and their guide Hans proceed on their epic journey, they encounter all kinds of strange, incredible sights. In chapter 30, they come across a world whose natural features strongly resemble those found on the earth's surface, except that they are much much bigger. Gazing around in wonderment as he stands in this gigantic crater, Axel is awestruck by the sheer vastness of everything; it is as if he is on another planet, like Neptune or Uranus.
Soon Axel's attention is drawn to an enormous forest. It is only a forest of mushrooms, says Otto, casually. But these are no ordinary mushrooms. They are giant mushrooms, thirty to forty feet high, crowned with a cap of equal diameter. There are thousands of them that are so densely packed together that they blot out the light when you stand beneath their giant canopies.