Roz is a sentient, highly adaptable robot living on a wild island. Gifted with a new, waterproof body by her human creator, she possesses immense physical strength and a deep capacity for empathy. When a toxic pollution cloud threatens her island home, she walks into the ocean to find a solution. She firmly values peaceful conflict resolution over violence.

Brightbill is an adult goose who was adopted and raised by Roz. He has matured into a leader within his flock and arrives home with a new mate, ready to start a family of his own. He is intensely loyal to his mother and attempts to support her when the poison tide arrives on their shores.

Gurry is an ancient, blind shark estimated to be over 500 years old. Known to the sea creatures as the Ancient Shark, Gurry serves as a scarred, resilient leader for the ocean animals. The shark holds crucial information about the source of the poison tide and organizes the sea creatures to defend their habitat.

Akiko is the human manager of a deep-sea mining operation. She struggles with the isolation of her job and being far away from her family on land. Though she oversees the excavation that generates the poison tide, she considers herself an employee simply following orders from higher authorities.

Crusher is a colossal, crab-like mining robot designed to demolish rock. Lacking Roz's sentience and empathy, the machine operates strictly on human programming to continuously extract minerals. Its relentless grinding generates the toxic dust that poisons the ocean.

Glimmer is a female goose who lost her parents during migration and found a partner in Brightbill. She is supportive, practical, and focused on building a safe nest for her incoming clutch of eggs.

George is the assistant manager at the Juggernaut mining station. He exhibits a strong distrust of rogue robots and defends the mining operation as a necessary function to create more technology.

Nimbus is a seagull suffering from an infected eye and missing feathers after eating contaminated crabs. The bird keeps Roz company while she hides and provides intelligence about the mining station.

Limber is an octopus with extraordinary camouflage skills. She guides Roz past dangerous breakers and expresses deep concern for the future of her eggs due to the spreading pollution.

Leo is Akiko's partner who lives on land with their daughter. He misses Akiko and expresses frustration over her long absences required by her job.

Kerplunk is a puffin who points Roz toward a glacier, giving her crucial directions to find the Ancient Shark in the northern waters.

Big Shot is a giant bull walrus who leads his herd. He steps in to boldly defend a young, stranded walrus from a hungry polar bear.

Dr. Molovo is the human creator and scientist who provided Roz with her advanced, watertight body. Though not present on the island, her engineering choices directly enable Roz's underwater journey.

Scoot is a hermit crab who uses a tin can for a shell. He introduces Roz to other displaced marine creatures in a submerged human town.

Ripple is a Gobie fish capable of changing gender. The fish explains this natural phenomenon to Roz, helping the robot feel more connected to nature's adaptability.

Zap is an electric ray who initially attacks Roz out of a defense response. Following the misunderstanding, he shares information about the Ancient Shark.

Loudwing is a goose who lives on the island and acts as a babysitter for Brightbill and Glimmer's young flock while they manage community issues.

Quickwit is one of Brightbill and Glimmer's newly hatched goslings. The young bird quickly observes how important Roz is to bringing the island community together.

Lighteyes is another of Brightbill and Glimmer's goslings who playfully dubs their mixed-species group a strange family.

Swooper is an owl who remains on the island as one of the more determined birds. He acts as an aerial scout, checking the coastlines for pollution levels.