Beneath the surrounding ocean lies Quetzo, a sunken Millhouse island now home to many sea creatures, which unlike Iloka, has many modern influences.

The series follows Lopaka, a young Polynesian boy who has the mysterious power to communicate with sea creatures and hold his breath for long periods underwater.

Lopaka, Flipper and their friends must work together to thwart the plans of the nefarious Dexter, an octopus wanting to claim Quetzo as his own, and keep peace amongst the underwater domain.

Lopaka (voiced by Jamie Oxenbould) - an 11-year-old Polynesian boy, referred to in the show as a menehune, who has the power to converse with sea creatures and to hold his breath underwater longer than possible.

The islanders of Iloka often wonder where Lopaka disappears to every episode, but he usually manages to avoid speaking the truth (up until Season 3).

Ray is kindhearted, and acts as a central motivator of the group, and Puffy, albeit insecure about himself, uses his ability to puff himself out to his advantage.

Even though Serge is to credit for the ideas that are made to destroy Flipper, whenever they go wrong, Dexter puts the blame on him for everything.

Finn, Nip, and Bubbles - three great white sharks who work for Dexter as brainless minions.

Nola - a young Polynesian girl who wears a simple Yellow dress and a leg bracelet around her right foot.

Bolo - a young fat Polynesian boy who is the Chief's son and likes to mess around with Lopaka.

She is good hearted and her son, Spike, is friends with Lopaka and is surprised the Milihune can get along without 20th century essentials.

Goose, Troy's off-beat assistant is a young man of few words; every time he speaks, he does so with an accent.

After a few incidents, Ultra proves herself a true, worthy companion, and Flipper gladly takes her into the group.