Audience reactions to blockbusters are difficult to predict, but it’s unlikely anyone will come out of “Aquaman” asking “Is this all there is?”

Not only does the new comic book superhero movie from the DC Extended Universe clock in at an over-extended 2 hours and 23 minutes, it throws everything at us except an undersea kitchen sink.

Anchored in the submerged citadel of Atlantis, “Aquaman” offers up wave after wave of heroes and villains, plots and counterplots, climaxes, anti-climaxes and CGI creatures, like a whole season of vintage “Star Trek” stuffed into one film.

That cover-the-waterfront attitude also extends to the casting. If anyone ever imagined seeing a superhero film where the supporting players include Nicole Kidman and Dolph Lundgren, Willem Dafoe and Temuera Morrison, not to mention the digitally altered voice of Julie Andrews as a sea creature, this is the dream they dreamt.


It’s almost as if director James Wan and screenwriters David Leslie Johnson-McGoldrick and Will Beall feared this would be their only shot at making an “Aquaman” movie and shoehorned every last idea they had into the mix.

As it turns out, they didn’t have to worry.

Notwithstanding the inevitable formulaic dialogue and a superabundance of boilerplate superhero action sequences, “Aquaman” turns out to be, almost despite itself, an engaging undersea extravaganza.


That’s because two key elements of this multipronged production work as advertised: the casting of Jason Momoa as Aquaman and Amber Heard as his fierce ally Mera, and the visual splendors of Atlantis and the submerged universe it is part of.

Already having made a fine first appearance as a vibrant superhero who just wanted to be left alone in 2017’s “Justice League,” Momoa is ideally cast as the half-human, half-Atlantean, totally tattooed protagonist.

Able to be both fierce and funny, he’s capable of holding a trident like he means business as well as delivering a string of verbal zingers: “I’m missing happy hour for this” he cracks when a rescue mission runs long.

Heard also made a brief appearance as the flame-haired Mera in the “Justice League” film, and she convincingly turns that Atlantean princess into Aquaman’s equal partner in derring-do, with the pair’s on-screen rapport becoming one of the production’s pluses.


“Aquaman’s” other advantage is the creation of Atlantis and environs. With cinematography by Don Burgess, production design by Bill Brzeski, costumes by Kym Barrett and visual effects supervised by Kelvin McIlwain, this is a film you don’t even want to think about watching on your cellphone.

It’s not just the great sense of underwater spectacle this team creates, complete with immense ancient statues and sea horses that really live up to the name, it’s that the effects make you believe the characters are actually living and breathing under the sea — even though filming on sound stages with wires and rigs was the order of the day.

When it comes to the actual plot all these people are swimming in, it is mostly acceptable if not particularly original — familiar elements like a treasure map to be followed and an Arthurian sword-in-the-stone motif find their place.

“Aquaman” starts, not surprisingly, with an origins story: telling how Aquaman’s lighthouse keeper father, Tom Curry (Morrison), came to find and rescue his mother, Atlanna (Kidman), queen of Atlantis.


Temuera Morrison as Tom Curry and Nicole Kidman as Atlanna in “Aquaman.” (Warner Bros. Pictures)

This meet cute leads to love and to the birth of son Arthur, the future Aquaman, but to keep the boy and his father safe, Atlanna returns home. Though she says she will return, the boy grows to manhood without ever seeing her again.

After a rocky childhood (a scene of his unique communication with fishes in the Boston Aquarium is a especially good), Arthur grows up to be a kind of freelance superhero, rescuing folks when it suits him and drinking beer when it doesn’t.

A battle against nautical pirates at the film’s opening turns out to have a lasting negative effect: One of the vanquished eventually becomes sworn enemy Black Manta (Yahya Abdul-Mateen).


Meanwhile, under the sea, Aquaman’s conniving half brother Orm (Patrick Wilson) is ruling Atlantis and, in combination with Nereus (Lundgren), is plotting to unite all the undersea tribes and declare war on the surface, payback for all the years of crass pollution of the oceans.

This disturbs Vulko (Dafoe), a top Atlantean adviser, as well as Mera, and she shows up unannounced to convince Aquaman that he should return home and, as the eldest son of the queen, claim the throne that is his birthright.

Aquaman, however, is unsure. Not only is responsibility not his thing, he is acutely conscious of his status as what King Orm dismissively calls a half-breed.

For in addition to its too-numerous plot elements, “Aquaman” turns out to be determined to convey positive messages about the virtues of inclusion and the need to clean up the planet.


When you throw in some emotional surprises, that’s a lot of boat for one movie to float, but float is what “Aquaman” manages to do. Could that be a sequel hovering on the horizon? I wouldn’t be at all surprised.

-------------

‘Aquaman’

Rated: PG-13 for sequences of sci-fi violence and action, and for some language

Running time: 2 hours, 23 minutes


Playing: Opens Dec. 21 in general release

-------------

ALSO

Justin Chang’s best movies of 2018: ‘Burning’ and ‘First Reformed’ lead a year of mystery


Mark Olsen’s best movies of 2018: ‘If Beale Street Could Talk’ stands out in a year that tried to make sense of madness

Kenneth Turan’s best movies of 2018: ‘Black Panther’ and ‘Leave No Trace’ top a banner year

kenneth.turan@latimes.com

@KennethTuran