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 Streets Under the Sky Times" called the series "a dreamy but gritty period drama, superbly acted" and "the kind of television at which the BBC repeatedly excels – rich and fulfilling for its understatement, discreet tales that are well told." "Variety" praised the series, writing it "brims with a sense of yearning that takes the very old quandary of not being able to control who one loves and puts an evergreen spin on it. Moreover, the production itself is as meticulous as the storytelling, from the drab palette used in capturing the Depression-era surroundings to the melancholy score." Twenty Thousand Streets Under the Sky