SpongeBob, Patrick, and Sandy attempt to stop an erupting volcano from destroying Bikini Bottom. Meanwhile, Plankton sees this as his time to strike.

"The intrepid Professor Lindenbrock embarks upon the strangest expedition of the nineteenth century: a journey down an extinct Icelandic volcano to the Earth's very core. In his quest to penetrate the planet's primordial secrets, the geologist - together with his quaking nephew Axel and their devoted guide, Hans - discovers an astonishing subterranean menagerie of prehistoric proportions. Verne's imaginative tale is at once the ultimate science fiction...