Dark Waters (Once Upon a Time) is to take Snow's heart. The Land of Untold Stories is revealed to be the Mysterious Island from the book as the same name. The "Nautilus" is based on the submarine from "Twenty Thousand Leagues Under the Sea". Captain Nemo based on the protagonist from Jules Verne's novel "Twenty Thousand Leagues Under the Sea". Hook refers to the giant squid that attacks him as a kraken. The kraken is a legendary sea monster of giant size that is said to dwell off the coasts of Norway and Greenland. The episode posted its lowest numbers so far in the series, as
Science fiction accuracy, especially "Twenty Thousand Leagues Under the Sea" (1870) which predicted the modern nuclear submarine. In 1887 the novel "El anacronópete" by Spanish author Enrique Gaspar y Rimbau introduced the first time machine. Many critics consider H. G. Wells one of science fiction's most important authors, or even "the Shakespeare of science fiction”. His most notable science fiction works include "The Time Machine" (1895), "The Island of Doctor Moreau" (1896), "The Invisible Man" (1897), and "The War of the Worlds" (1898). His science fiction imagined time travel, alien invasion, invisibility, and biological engineering. In his non-fiction futurologist works he predicted