Far be it from me to judge other nations, but there’s something rotten at the core of Atlantis, the underwater setting of the new DC Comics blockbuster Aquaman. The realm’s monarchical system of primogeniture has handed the throne to a warmongering maniac named Orm (played by Patrick Wilson). Relationships with the crab people of the Brine kingdom and the spiky monsters of the underwater trenches are at all-time lows. And the nation’s only plan to combat global warming is to try to invade the surface with an army on shark-back. Wait, does this all sound like a bizarrely complicated piece of high fantasy rather than a goofy comic-book film? I have great news for you, reader: It’s both.

James Wan’s Aquaman has no business being a good movie. It barely has business being a movie at all, given that DC Comics’ undersea hero has long been a butt of pop-culture jokes rather than a big seller, best known for talking to fish and having little to offer the Justice League when their adventures take place on the surface world. But this is 2018, the world is immersed in superhero movies, and Warner Bros. insists on having a robust “cinematic universe” for folks such as Superman, Batman, and Wonder Woman to tool around in.

Enter Jason Momoa’s Aquaman. A thickly bearded, trident-wielding beach bro, he first made a cameo appearance in Batman v. Superman and then was given a little more to do in 2017’s Justice League. In that film, he was largely relied on to occasionally spear a monster or shout bits of encouragement such as “My man!” to his more famous teammates. Momoa, still best known for his work on Game of Thrones, gave an affable performance that suggested any potential solo film would have a freewheeling, surfer-movie vibe.

Not so much. Instead, in the hands of Wan (who created the Saw, Insidious, and Conjuring franchises and more recently directed Furious 7), Aquaman is a hilariously dense, intensely nerdy, and sublimely silly project, one where discussions of oceanic parliamentary law exist alongside a giant octopus playing the drums. It’s a film that feels more indebted to the assuredly zany work of directors such as the Wachowskis (particularly Jupiter Ascending) and Luc Besson (Lucy, Valerian) than to grim-and-gritty DC Comics movies such as Suicide Squad. And it’s anchored by Momoa’s easy-breezy approach, which keeps matters from ever feeling too overwhelming or arcane.

The plot of Aquaman? It’s simple: Aquaman is Arthur Curry, the product of a star-crossed romance between the lonely lighthouse keeper Thomas Curry (Temuera Morrison) and the Atlantean queen Atlanna (Nicole Kidman). Raised on the surface, Arthur can nonetheless breathe underwater, talk to fishies, swim at superfast speeds, and whirl a weapon around in all kinds of cool ways. But having lost his mother under mysterious circumstances long ago, he’s uninterested in his royal heritage—until the sea princess Mera (Amber Heard) shows up and tells him he needs to find a mythical trident and save the world.

Most of Aquaman is a quest movie, with Arthur and Mera zipping from location to location (including the Sahara and Sicily) in search of trident clues, while the villainous Orm gathers his armies (mounted on sharks) to prepare to conquer us landlubbers. But then: There’s Dolph Lundgren as a seahorse-riding rival king whom Orm needs to form a political alliance with. There’s Vulko (Willem Dafoe), Orm’s grand vizier, who is playing both sides and secretly aiding Arthur. There’s the Black Manta (a wonderfully imposing Yahya Abdul-Mateen II), a submarine pirate who seeks personal vengeance against Arthur. There’s a lot of chatter about diplomatic clearance and ancient treaties. Julie Andrews voices a 1,000-foot-tall leviathan.

There’s a lot going on in this movie, and Wan happily dumps it all in the viewer’s lap, highlights it in various shades of neon, and dials the visual inventiveness up to maximum. This is a sensory-overload movie, but in a good way—the action isn’t chopped to pieces and dully rendered as in so many superhero movies, and the film never pauses to address some unrelated spin-off or sequel in the DC world. This is a story about the fraught political situation of Atlantis, and the necessity of a consensus-building, holy-trident-wielding half-human coming in to institute various reforms. Some of those reforms might involve giant crab people. If you have a problem with that, the exits in your theater are clearly marked.

Aquaman serves as further evidence that the DC Universe can thrive if it embraces the grander sincerity of its godlike heroes rather than trying to ground them in the real world. Yes, Momoa knows how to have a good time amid all the underwater special effects and encyclopedic world-building. There’s plenty of humor and fun to be found in a film where Dolph Lundgren rides a giant seahorse into battle. But Aquaman works because it isn’t laughing at itself—it’s both joyously whimsical and confident in its own seaworthiness.