Even sea beasts are adorable when they’re babies. But watch out when they get big! They can smash the hull of a ship with their giant horns, or pull a boat to the bottom of the ocean with long, snake-like tentacles. At least, that’s consistent with the legends we were told when unfinished maps labeled uncharted waters “here there be monsters.” But what if those monsters were real? That’s the jumping-off point for Disney veteran Chris Williams’ first Netflix feature, “The Sea Beast,” a spectacular high-seas adventure of the kind most directors know better than to attempt.

But Williams had a distinct advantage: He’s an animator. The accomplished cartoon helmer, who cut his teeth on “Bolt” and “Big Hero 6,” first took to the open waters with “Moana” — a dry run of sorts for some of the thrilling ideas he hoped to implement here. “Never work with kids or animals,” experienced film crews caution. “Stay on dry land, if at all possible.” When live-action filmmakers disobey those rules, the job winds up being far more difficult than they bargained for. (“Waterworld” anyone?) But if making an animated movie, why not embrace those obstacles?

In the end, “The Sea Beast” is a movie about challenging conventional wisdom and figuring things out for yourself, and that’s a philosophy that worked on both sides of the camera. Its two main characters are both orphans who lost their parents at sea, doing battle with terrifying dragon-like creatures. The similarities to DreamWorks’ “How to Train Your Dragon” franchise will be lost on no one.

In the impressively staged prologue, “The Sea Beast” shows young Jacob Holland — you may as well call him Ishmael — clutching to shards of a broken boat. It’s a breathtaking sight, rendered all the richer via you-are-there sound design and Mark Mancina’s classical horns-and-drums score. The ship blazes red above water before the virtual camera plunges below the surface to reveal the hull torn in two. This traumatic sea beast attack gave Jacob’s life meaning: Rescued soon after by one-eyed Captain Crow (a salt-and-vinegar-sounding Jared Harris), he will spend the rest of his days chasing these creatures to the ends of the earth.

The movie’s other orphan, a Black girl named Maisie Brumble (Zaris-Angel Hator), is a good deal younger. Both of her parents were “hunters” — the naval heroes dispatched by the king and queen to keep the monsters in check — who went down with the Monarch. Now stuck in a group home, Maisie reads books about how courageous sailors like her mom and dad fought the beasts that once attacked human towns, plotting her escape, so that she might join the hunters. At a tavern in town, she begs Jacob to bring her along. It’s a great scene, whose dialogue — like the lively body language and facial expressions — reveal the characters’ individual personalities and the assertive way this girl addresses grown-ups.

Maisie is more than just precocious; she’s downright disobedient, which is consistent with the recent trend in studio animation where defiant kids were put on this earth to teach their elders a lesson (see “Turning Red,” “Luca” and “Encanto,” wherein conventional villains have been replaced by obstinate adults). Taking another page from “How to Train Your Dragon,” “The Sea Beast” concerns a civilization built on the premise that humans must unite against dangerous supernatural species. But what if the books are wrong?

Back in the orphanage, Maisie believed every word of what she read. After stowing away on the Inevitable, she’s thrilled to be meeting her heroes — a motley group of characters, whose diversity is a welcome departure from other pirate-movie ensembles. But she’s not too shy to question their assumptions, even going so far as to cut the ropes mid-battle with the Red Bluster, the Moby Dick of sea beasts, a scarlet colossus with powerful jaws and a snout like a boiled lobster’s claw, which Capt. Crow has been chasing for nearly three decades.

Maisie’s actionsspares the ship, but not without consequences, as the monster swallows both her and Jacob and swims off to its island sanctuary. Now, Williams and co-writer Nell Benjamin have the tough job of changing the pair’s minds in the span of a few scenes. Remember, both characters have lost loved ones to these predators, and they spend a not-insignificant amount of time in the belly of the beast, like Jonah or Geppetto. But once they reach the island, the two survivors quickly switch from wanting to destroy all monsters to teaming up with “Red” to face down other threats together.

Williams stages an exciting Godzilla-like battle between Red and a giant purple crab, along with a couple brisk bonding scenes with baby sea beasts. In one, a giant yellow slug-creature chases Jacob, until he realizes that this agitated mama was just trying to protect her young. (From this, Williams means for us to extrapolate that sea beasts are benign unless threatened — a leap that asks audiences to ignore everything they know about wild animals.) In another, Maisie finds a blob-like mini-beast with rubbery indigo skin and widely spaced eyes, the sort that make internet sensations of deformed cats. She dubs him “Blue,” and immediately tries to domesticate the little guy.

“That is not a pet!” Jacob insists, but who is he kidding? The rest of “The Sea Beasts” finds him and Maisie trying to convince the king and queen and all their subjects that monsters are not to be feared — which is another idea that almost certainly would’ve failed, if the project had been done via live action. Animated by the pros at Sony Pictures Imageworks, the film features incredibly nuanced facial expressions and dynamic camera moves (watch it swoop among the ship’s masts during the Bricklebat attack). A few of the backdrops look convincing enough to be real locations, but this is a cartoon through and through.

Still, Williams manages to sell the twist by appealing to audiences’ sympathies (’80s movie “Baby: Secret of the Lost Legend” comes to mind, as animal lovers try to protect an endangered brontosaurus from evil poachers). The results, while not entirely convincing, are just gorgeous — worth seeing on the big screen if at all possible. Just don’t let your kids try to convince you that killer whales are our friends, or that “Jaws” was such a lie that we needn’t be wary of sharks.