Follows an underwater exploring crew made up of stylized anthropomorphic animals, a team of eight adventurers who live in an undersea base, the Octopod, from where they go on undersea adventures with the help of a fleet of aquatic vehicles.

The Octonauts expand their exploration beyond the sea -- and onto land! With new rides and new friends, they'll protect any habitats and animals at risk.

During World War II the passenger liner "Goliath" is sunk by a German submarine. Portions of the ship's hull remain airtight, and some of the passengers and crew survive. Over the decades they build a rigidly regulated society completely isolated from the surface world until, in contemporary times, a diving team begins to explore the wreck.