Jason Momoa takes to the seas once more as Arthur Curry in the first trailer for director James Wan's Aquaman, released today during the Warner Bros. Hall H presentation at Comic-Con International.

As we would expect from a teaser, it's heavy on set up, establishing Arthur as first a boy, and then a man, caught between two worlds: the surface and Atlantis. It also confirms much of what we already knew about the film's premise, with Momoa's reluctant king returning to the sea to claim the throne from his half-brother Orm (Patrick Wilson), who plans to make war on the surface world as retribution for its centuries of pollution.

From Warner Bros. Pictures and director James Wan comes an action-packed adventure that spans the vast, visually breathtaking underwater world of the seven seas, Aquaman, starring Jason Momoa in the title role. The film reveals the origin story of half-human, half-Atlantean Arthur Curry and takes him on the journey of his lifetime—one that will not only force him to face who he really is, but to discover if he is worthy of who he was born to be…a king.

However, it's not all backstory. Exactly five months away from the release of James Wan's film, the trailer delivers plenty of set pieces, CI creatures, action sequences and enough underwater scenes to establish that Aquaman may pull off the trickiest parts. Atlantis, whose buildings resemble so many enormous jellyfish, also impresses.

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Arriving Dec. 21, director James Wan’s Aquaman stars Jason Momoa as Arthur Curry, Amber Heard as Mera, Willem Dafoe as Vulko, Patrick Wilson as Orm/Ocean Master, Dolph Lundgren as King Nereus, Yahya Abdul-Mateen II Black Manta and Nicole Kidman as Atlanna, with Ludi Lin as Captain Murk and Temuera Morrison as Tom Curry.