“Aquaman” won’t surface until Christmas of 2018, Warner Bros. said on Thursday.

The comic book adaptation is swimming from an Oct. 5 release date to Dec. 21 of that year. It will open on the day that “Avatar 2” was originally slated to debut. The James Cameron-directed sequel has been delayed multiple times as the exacting filmmaker tinkers with his latest cinematic excursion into Pandora. Jason Momoa, best known for his work as Khal Drogo in the HBO series “Game of Thrones,” stars in “Aquaman” as the titular merman. James Wan (“The Conjuring”) directs.

The studio has a lot riding on “Aquaman.” Warner Bros. has invested heavily in crafting a cinematic universe of DC Comics characters to rival the one established by Marvel, with mixed success. Both “Batman v Superman: Dawn of Justice” and “Suicide Squad” were commercial hits, but they were bashed by critics, signalling that quality control will be important going forward. Aquaman had a cameo in “Batman v Superman” and has a larger role in next fall’s “Justice League,” a film about a super-team of spandex-rocking heroes that features the Dark Knight, Man of Steel, and Wonder Woman. In its new slot, “Aquaman” will square off against Sony’s animated Spider-Man movie.

Warner Bros. also announced that “Horse Soldiers” will debut on Jan. 19, 2018. The film follows a team of CIA agents as they try to break up the Taliban in the wake of 9/11. Chris Hemsworth of Thor fame heads up a cast that includes Trevante Rhodes, Michael Shannon, and Michael Pena.

“Bastards,” an Owen Wilson and Ed Helms comedy that was yanked from its Jan. 27 debut, will instead bow on Dec. 22. The buzz on the film internally is that it’s not funny. It will face fierce competition when it launches. That holiday period will also see the debuts of “Pitch Perfect 3,” a remake of “Jumanji” with Dwayne Johnson and Kevin Hart, “Downsizing,” an Alexander Payne comedy starring Matt Damon, and “The Six Billion Dollar Man,” an action-thriller with Mark Wahlberg. That suggests that it may be looking less at a premiere date than a wide-release euthanization.

Insiders at the studio counter that the film has been warmly received in test screenings and will be best served by a Christmas season release, noting that comedies such as “Sisters,” “Why Him?,” and “Daddy’s Home” have thrived during the holidays.

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