The ability to transform from sea monster to human not only opens the door to Luca’s life-changing adventure—it serves as subtle explanation. “It’s an adaptation—like camouflage,” says director Enrico Casarosa. “It explains why sea monsters haven’t been noticed in this world for centuries.”

According to character supervisor Beth Albright, the transformation had to be both physical and—at times—emotional. “Enrico really wanted the transformation to be something that’s happening to the character, rather than a suit that slides on or off of them,” she says. “It had to be internal—something that the character would react to—but nothing that felt creepy. We opted for a transformation that would ripple through the body.”

Luca Paguro is a bright and inventive 13-year-old sea monster with endless curiosity—especially when it comes to the mysterious world above the sea. Although he’s been warned his whole life that the human world is a dangerous place, he longs for something beyond his quiet farm life where he herds goatfish day after day. So when another sea monster with actual experience above the surface takes Luca under his fin, his eyes open up to a whole world of possibilities.

Alberto Scorfano is an independent, free-spirited teenage sea monster with unbridled enthusiasm for the human world. Expressive and gregarious, he is all about having fun, so inviting a fellow sea monster to hang out above the surface is a no-brainer for Alberto. Besides, Luca is the perfect audience for Alberto’s vast—albeit questionable—knowledge of all things human.

Giulia Marcovaldo is an outgoing and charming adventurer with a love of books and learning. She only spends summers in Portorosso, so she hasn’t cultivated many friendships, which makes her an easy target of the town bully. But when two new kids show up who clearly need an ally, Giulia is more than happy to oblige—especially when they agree to team up with her in a local race she desperately wants to win.

Ercole Visconti is the bully of the small Italian town of Portorosso and repeat champion of the town’s Portorosso Cup race. He’s a Vespa-owning, pompadoured blowhard who believes that everyone loves him and enjoys watching him eat sandwiches. He has two worshipful followers, Ciccio and Guido, who accompany him everywhere, ready to do his bidding. 

Giulia’s dad, is an imposing, tattooed, one-armed fisherman of few words. Luca and Alberto can’t help but be intimidated by his formidable size and skill with a knife, but Massimo has a soft heart, especially for his daughter.

Daniela Paguro is Luca’s loving mother, who’s determined to keep her son safe. She regularly warns Luca of the dangers beyond the sea and the land monsters who live there. Daniela is no pushover: If she thinks Luca is breaking her number-one rule—don’t go near the surface—she’ll go to great lengths to stop him. 

Grandma Paguro and Luca have an understanding. She sees the spark in her grandson’s eye, his longing for more, and celebrates it—albeit secretly. Grandma knows that breaking a rule or two is part of growing up, and she’s a little too happy to look the other way if Luca’s rebellious side should emerge.What his parents don’t know probably won’t kill them.

Uncle Ugo,perhaps Luca’s strangest and most bizarre relative, emerges from the deepest part of the ocean to help Daniela and Lorenzo convince Luca of the dangers of the surface. Like Luca, Ugo once wondered about the world beyond the surface. But following a near-death encounter he learned to steer clear, relocating to his deep-water home where it’s pitch dark, bitterly cold and far, far away from the scary humans above the sea—just the way he likes it.

Machiavelli is Giulia’s sweet-natured pet cat—sweet natured to humans, that is. When Machiavelli meets Luca and Alberto, he immediately senses there’s something fishy about them. And he loves the taste of fish.

Director Enrico Casarosa decided early on in the production that the film should feel as if it were from the Luca’s point of view. To that end, the Italian seaside setting conjures an immediate sense of wonder. Completing the magical transformative feeling of the main character’s escapism Casarosa envisioned is the carefree idea of summer time, a truly nostalgic era and a stunning painterly style. “The artist’s hand is something I think a lot about,” says Casarosa. “We try to bring some of that warmth and imperfection to the computer animation. And our story takes you to a place that’s fantastic, but also inspired by where I grew up.”

According to color & shading art director Chia-Han Jennifer Chang, the palette of the setting was influenced by the era—but enhanced to reflect the unique point of view. “We wanted to capture the idea that it’s a child’s memory of that summer, so everything is way more vibrant—bigger and more saturated than reality,” says Chang.

Although the town of Portorosso is entirely fictional, the feeling it conveys of the Italian Riviera is familiar—a nod to the Cinque Terre in Liguria, Italy, says sets supervisor Chris Bernardi. “The town itself really tells a story,” he says. “These old stucco buildings that have been worked on and improved. There’s a pescaria, a gelatoria and a foccaciaria. There’s an old restaurant and a new one. The church is on the square near the cinema.”

Kim White, director of photography, was fascinated with the narrow streets and alleyways. “I brought home from Italy pictures of the way the light fell between the buildings and bounced off of them,” she says. “I wanted to capture the beautiful quality of the light in town and the interesting shadow compositions that I saw there.”

Luca’s family lives in a modest underwater home where they farm kelp and herd goatfish. According to director of photography David Bianchi, filmmakers wanted to make this underwater world appealing—but not too appealing. “This is where we meet Luca and learn pretty quickly how much he thinks about life beyond the surface,” says Bianchi. “How do we make that location something that our protagonist would want to leave?”

Once Alberto is able to coax Luca out of the water and demonstrate that he is not only safe but able to see a whole new world—the sun, the sky, birds—he shows off his hideout—a reclaimed old Roman tower that was long-ago abandoned. “It’s falling apart,” says sets supervisor Chris Bernardi. “The stairs are broken, so Alberto’s built a ladder up to the one floor that still exists—barely.”

Story lead McKenna Harris says, “It tells two stories: it hints at what might be a troubling backstory for Alberto, but on the other hand, it’s every kid’s dream to have a place of their own where imagination rules. We all want to hang out there. It’s charming and, at the same time, a little rough around the edges.”