Join the Octonauts as they journey to Antartica to prevent a group of penguins from falling into an ice chasm. Come along with Captain Barnacles as he teams up with his niece and nephew, Ursa and Orson, to rescue walrus pups. And when the Octonauts explore a hidden lake sealed by ice for millions of years, Shellington discovers microscopic creatures still living under the ice.

Cookiecutter sharks: Captain Barnacles and the crew investigate why mysterious holes have started to appear in their equipment -- Lost lemon shark: The underwater explorers go in search of a lemon shark that has hurt its nose and is struggling to find its way home -- Dwarf lantern shark: Captain Barnacles and the team try to find an injured dwarf lantern shark -- Giant jelly: The crew tries to rescue Peso when he becomes trapped inside a giant jelly...