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 seas and charted all oceans. Verne would have known of Matthew Maury's international fame and perhaps Maury's French ancestry. References are made to other such Frenchmen as Jean-François de Galaup, comte de Lapérouse, a famous explorer who was lost while circumnavigating the globe; Dumont D'Urville, the explorer who found the remains of Lapérouse's ship; and Ferdinand Lesseps, builder of the Suez Canal and the nephew of the sole survivor of Lapérouse's expedition. The "Nautilus" seems to follow the footsteps of these men: she visits the waters where Lapérouse was lost; she sails to Antarctic waters and becomes stranded there, just