Jason Momoa, in the title role, turns out to be a sizable asset, a reference that goes beyond his super-heroic physical qualities. The real star here, though, is director James Wan (a veteran of "The Conjuring" and "Fast & Furious" series), who creates an unabashedly comic-book-immersive world — with the occasional clumsiness that entails — while lightening the mood considerably from the darkness into which some of DC's prior efforts descended.In a sense, Wan brings the same eye that "Batman v Superman" director Zack Snyder possesses in adapting comic-book images to the screen, without drowning his protagonist in angst. The result is a movie that's fairly buoyant, and to use a term that might seem out of place when describing a special-effects-laden blockbuster, generally fun.After two appearances in earlier films (one, admittedly, silent and brief), Aquaman finally gets a full-blown origin story, including the tale of how his mother (Nicole Kidman) — a runaway Atlantean princess — washed ashore and met his dad ("Star Wars" alum Temuera Morrison), hanging around long enough to give birth to a son, Arthur.Forced to return to Atlantis and its elaborate society hidden beneath the waves, she leaves the boy to grow up with his dad, a youth that's complicated when those extraordinary abilities manifest themselves.Back to present day, a threat arises in the form of Arthur's half-brother, Orm (Patrick Wilson), who is determined to declare war on the surface-dwellers. Aquaman is enlisted to stop the plot by another rebellious Atlantean princess, Mera (Amber Heard), who is putting her own status at risk — and potentially alienating her father (Dolph Lundgren) — by siding with him.What amounts to a quest ensues, one necessary to give Arthur a fighting chance against the forces arrayed against him. That also creates a little too much opportunity for Aquaman and Mera to squabble and of course bond, while crisscrossing the globe in pursuit of a trident imbued with fantastic powers.There's no escaping that the dialogue feels strained in places — it's not easy taking a villain seriously who yearns for the title "Ocean Master" — and "Aquaman" requires a certain degree of buy-in, perhaps especially from those whose familiarity with the character begins and ends with "Super Friends." Wan compensates for that, however, with the enormously intricate civilization that he conjures, from the fantastic beasts to the towering spires of Atlantis.The action, similarly, is both kinetic and mounted with the kind of scale where a submarine can be thrown around like a toy. And while the idea of a reluctant hero tasked with fulfilling his destiny is hardly a new one, Momoa alternately makes him irascible and actually kind of goofy — the first member of this DC universe with whom you might actually like to throw back a beer or three.Perhaps foremost, Wan offers a giant spectacle that, while sporadically unwieldy, sails along briskly enough (despite running well over two hours) and proves consistently interesting visually. In an cinematic age where part of the challenge is motivating people to see movies during their theatrical window, "Aquaman" feels like a master of that domain."Aquaman" premieres Dec. 21 in the U.S. It's rated PG-13. Like Warner Bros. and DC Entertainment, CNN is a unit of WarnerMedia.