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 crew member who died when an accident occurred under mysterious conditions inside the "Nautilus". When the "Nautilus" returns to the Atlantic Ocean, a pack of "poulpes" (usually translated as a giant squid, although in French "poulpe" means "octopus") attacks the vessel and kills a crew member. Throughout the story Captain Nemo is suggested to have exiled himself from the world after an encounter with the forces that occupied his country that had devastating effects on his family. Not long after the incident of the poulpes, Nemo suddenly changes his behavior toward Aronnax, avoiding him. Aronnax no longer feels the same