A fictional television show named Sea of Tranquility connects the Black Mirror universe, but what's the significance of it? Created by Charlie Brooker, Black Mirror is an anthology series that explores how technology influences modern society - and how it could continue to evolve in the future. The standalone interactive special Bandersnatch released in December 2018, and Black Mirror season 5 premiered on June 5, 2019. Black Mirror episodes typically include Easter eggs referencing other episodes, and “Sea of Tranquility” is used to complement themes of obsession and/or desperation.
Sea of Tranquility has been referenced in four Black Mirror episodes. The first mention comes in the series debut, “The National Anthem,” in which a Prime Minister (Rory Kinnear) is tricked into having sex with a pig on national television, in order to secure the release of a kidnapped Royal Family Princess. The fictional series is cited once again in the Black Mirror season 3 episode “Nosedive,” as a young woman (Bryce Dallas Howard) hopes to improve her social standing via technology that allows people to rate their personal interactions. There's another Sea of Tranquility reference in the Black Mirror season 5 episode “Smithereens,” which features Andrew Scott (Fleabag) as a traumatized man who seeks revenge against a prominent social media company. Finally, "Rachel, Jack and Ashley Too" has a news bulletin that references the reboot of the show.
In “The National Anthem,” the Prime Minister is told that he must have sex with a pig on live TV, or a kidnapped member of the royal family will be killed. In an effort to avoid actually going through with the act, his associates hire a special effects expert named Noel, who is identified as having won an Emmy Award for an “HBO moon Western thing” - which Noel identifies as Sea of Tranquility. He’s skeptical about time restraints for the pig project, but states that “with finessing, it should be OK.” Ultimately, a photo leak derails the plan and leads to online backlash.
“Nosedive” includes an extended sequence about the fandom associated with Sea of Tranquility. Towards the end of the Black Mirror episode, Howard’s character, Lacie, desperately attempts to reach a friend’s wedding as her approval rating rapidly drops. While seated at a charging station bathroom stall, she overhears a conversation between two young women who are headed to “Tranquility Con” in Port Mary. Lacie quickly researches the show, and secures a ride with an RV full of rabid fans who inquire if their new passenger is a "Tranq Head." Lacie’s Sea of Tranquility knowledge is questioned when she attributes specific genders to a character known as “Lieutenant Duster,” only to learn that said character “has no fixed gender.” Once Lacie reaches her destination, she yells out “Hope they cancel it!”
Approximately 23 minutes into “Smithereens,” Scott’s character, Chris, makes a hostage call his employer, Smithereen. In the main lobby, a large screen is set up behind the main desk. Breaking news references the aforementioned Black Mirror episode “The National Anthem,” as a headline reads “Prime Minister Callow to meet with EU negotiators in Brussels.” On the screen's left side, a group of trending topics are visible, including “SeaOfTranquilityReboot.” The ticker also references “SaitoXNetflix” and “SaitoGemuAnnouncement,” both of which are connected to the Black Mirror episodes “Playtest” (Season 3) and “Striking Vipers” (Season 5).
Finally, in "Rachel, Jack and Ashley Too," a news update on the health of pop star Ashley O (played by Miley Cyrus) mentions that there's more news about the upcoming Sea of Tranquility reboot on the way, indicating that this episode takes place at around the same time as "Smithereens." The references to a reboot are especially amusing because, if the show had to be rebooted, Lacie must have successfully cursed it with cancellation back in "Nosedive."