Aquaman takes 100 minutes worth of rollicking escapism and dilutes it into 145 minutes worth of movie. At some point, all the subplots and flashbacks and supporting characters and mythic beasts and sweeping aquatic battles amount to an overpacked suitcase, with the filmmakers sitting on it to get the latches shut. Jason Momoa is great and most of the rest of it is just good enough that it makes me wish they’d left a few more things at home. Or at least saved them for the inevitable sequels.

The recent, shambling DC movies may lack panache or nuance, but one thing they do have is some damn fine casting. Momoa’s Arthur Curry/Aquaman struts through this movie like a shredded, tatted-up badass. He only interrupts his pitchers of beer to take selfies with grubby fans and hand out well-deserved whoopins on the high seas. Unfortunately, Arthur’s laid-back superhero gig gets knocked off course in the form of some Game of Thrones-style intrigue.

Okay, deep breath: It seems Arthur’s mom (Nicole Kidman) ruled the underwater kingdom of Atlantis until she fell for a landlubber in a lighthouse (Temuera Morrison). She bears his son, a mortal sin that earns her probable execution at the hands of the king. Meanwhile, the vizier of Atlantis (Willem Dafoe) grooms young Simba Arthur to take his rightful seat on the throne. His main obstacles are Arthur’s ruthless younger brother Orm (Patrick Wilson, in full Corbin Bernsen Mode) and Arthur’s own reluctance to abandon his nomadic, ass-kicking lifestyle. Arthur gains a powerful ally in the form of Mera (Amber Heard), the water-wielding princess who seems destined to bicker and banter her way into Arthur’s burly arms. Oh yeah, a high-tech pirate swears vengeance on Aquaman for the death of his father. And we hear the legend of an ancient King and his missing trident. And the elders of Atlantis decree that the surface world should be obliterated. Phew!

If you think that sounds pretty plotty, you’d be right. This movie feels like a flabby slab of beef in need of a better butcher. Somebody somewhere should’ve sat down the writers and delivered an ultimatum: Either lose three subplots or thirty pages of script. You pick. And maybe I’m in the minority on this, but I am over the big, Attack of the Clones-style battles where armies of CGI characters shoot lasers at each other for ten whole minutes. Nothing’s going to happen to anybody the audience cares about, so what’s the point? There’s a protracted, boring sequence like that in this film, and it could’ve been scrapped entirely.

Despite all its flaws, Aquaman offers a lot to enjoy. Momoa clearly has a blast, and it’s infectious for the whole film. He delivers one-liners with a manly twinkle, and injects some desperately needed humor into the DC universe. Willem Dafoe and Nicole Kidman give a little gravitas to a movie that might otherwise drown in its own goofy plot. Heard does well as a mature counterpoint to Momoa’s aloof lumbersexuality. Only Wilson seems wasted and one-dimensional as an Atlantean Winklevoss twin.

Alfred Hitchcock once observed that movies had an obligation to be no longer than the endurance of a human bladder. Aquaman is long and feels like it. It doesn’t help the whole bladder thing that almost every scene has running water flowing through the rear speakers. Still, while Aquaman may not be as disarmingly charming as Wonder Woman, it’s leaps and bounds above anything else DC has done lately.