Axel faces a shocking sight: The men are standing on the shore of a huge subterranean body of water, whose other shore is lost in the distance. Because of its size, Otto names it “The Sea of Lidenbrock” (100). The shore they are standing on slopes down to something like a beach made of golden sand and small shells. Axel sees all of this without the help of a lantern because of a light coming from the electric charge produced by the cloud-like vapors filling the cavern.

Further down the shore, Axel notes what looks like a forest of petrified cedars, only to discover on closer inspection that the trees are gigantic mushrooms. There are other types of vegetation as well, but all of it is discolored. Additionally, the explorers find the bones of huge prehistoric animals, such as mastodons. Axel is puzzled by the existence of animals so deep under the surface of the Earth. Otto believes that the bones are part of a sedimentary crust that at some point fell into the cavern from the surface. Axel speculates on the continued existence of living monsters in this cavern but soon dismisses the notion.