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
20,000 Leagues Under the Sea: Submarine Voyage 20,000 Leagues Under the Sea: Submarine Voyage 20,000 Leagues Under the Sea: Submarine Voyage was an attraction at the Magic Kingdom theme park at Walt Disney World from 1971 through 1994. In 1959, an ambitious expansion of Tomorrowland in Disneyland was completed, which included the addition of new attractions, including the Matterhorn Bobsleds, Monorail, and Submarine Voyage. "Commissioned" on June 6, 1959, in front of Richard Nixon, Walt Disney and his wife Lillian, and officers of the US Navy, the attraction made use of early animatronics to create underwater life, and the use of forced perspective to increase the feeling