Development "Legend of the Sea Devils" was the final episode produced as part of the eight episodes ordered for the
thirteenth series of
Doctor Who. Despite this, it stands alone from the six-part series. Along with the
previous episode and the
following episode, which was ordered later, it is the second and penultimate episode in a
trio of specials. The episode was co-written by first-time writer for the programme,
Ella Road, along with the
showrunner,
Chris Chibnall. Road wrote the episode with Chibnall at his house in
Wales over the course of three days. Road stated that she initially expected Chibnall to have an idea for the story drafted when she was hired, but this was not the case.
Script editors Becky Roughan and Caroline Buckley also participated in brainstorming sessions. The
Sea Devils make their return in the episode for the first time since the 1984 serial
Warriors of the Deep. It is their third major televised appearance, following their introduction in
The Sea Devils in 1972. Chibnall revealed that he did not always have intentions to bring the Sea Devils back to
Doctor Who. One of Road's contributions was the addition of the historical figure
Zheng Yi Sao, also known as Madam Ching, to the special. Also depicted is the
Flor de la Mar, a
sailing ship that sunk off the coast of
Indonesia with stolen goods that were never recovered. Chibnall wanted to use these elements after a pirate-themed story had been planned for the thirteenth series but did not come to fruition. The episode also continued to explore the
same-sex romance between
the Doctor and her companion
Yasmin Khan. Road said that she and the producers insisted on handling the situation "delicately", but that they recognized the story needed to be told. She further explained this aspect of her writing in an edition of
Doctor Who Magazine, "I think it's good to be able to include these real relationship questions that people can relate to, outside the whole sci-fi aspect of the show. The question of whether or not to enjoy a relationship for what it is now, versus worrying about the future – that's a very universal thing." As part of the promotion for the episode, Scottish musician
Nathan Evans released a
Doctor Who-themed adaptation of the sea ballad "
Wellerman".
Casting Jodie Whittaker starred in the episode as the
thirteenth incarnation of
the Doctor.
Mandip Gill and
John Bishop portrayed the Doctor's
companions,
Yasmin Khan and Dan Lewis, respectively.
Crystal Yu was cast to play
Madame Ching while Arthur Lee and Marlowe Chan-Reeves guest starred as Ji-Hun and Ying Ki. David K. S. Tse appeared as Ying Wai. Craige Els, who portrayed Karvanista in series thirteen, played Marsissus, the chief Sea Devil, while Simon Carew, Andrew Cross, Jon Davey, Chester Durrant, Mickey Lewis and Richard Price were additional Sea Devils. Nadia Albina made an uncredited appearance as Dan's love interest Diane.
Filming "Legend of the Sea Devils" was directed by Haolu Wang. Known previously for her work on short films, the episode is Wang's television directorial debut. Filming was
impacted by the COVID-19 pandemic. Mark Waters was the episode's
Director of Photography.
Principal photography wrapped on 25 July 2021.
Executive producer Matt Strevens confirmed that the special was in
picture lock by February 2022. The updated designs for the Sea Devils were created by costumers Ray Holman and Maker Robert Allsop. In their original appearance, the Sea Devils wore outfits made of silver fish netting. The new look included revised outfits for the Sea Devils; however, Holman "included some nods to the original look, weaving netting through the costumes" and their armour. When creating the head pieces, Allsop took measurements from a cast that was created for the Sea Devils in the 1980s. He also used photos from their previous appearances. The newer masks enabled the Sea Devils to have "more realistic expression". ==Release and reception==