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
Twenty Thousand Leagues Under the Sea and begins to sympathize with Ned Land. Near the end of the book, the "Nautilus" is attacked by a warship of some nation that had made Nemo suffer. Filled with hatred and revenge, Nemo ignores Aronnax's pleas for mercy. Nemo—nicknamed "angel of hatred" by Aronnax—destroys the ship, ramming it just below the waterline, and consequently sinking it into the bottom of the sea, much to Aronnax's horror, as he watches the ship plunge into the abyss. Nemo bows before the pictures of his wife and children and is plunged into deep depression after this encounter. For several days after this,