When the Octopod breaks down, Tweak and the crew search for a missing part aboard an abandoned prototype of the ship, not realising something lives there.

When the Octonauts go on a pirate treasure hunt, Kwazii meets a Parrotfish.

The gang ventures into a red-hot lava tube to rescue a tiny water bear that does not seem to mind the heat at all.

The Octonauts must evacuate sea creatures before an underwater volcano erupts, but there's one creature that won't budge: a slow moving, gelatinous Blobfish.

The Octonauts must rescue Peso when he gets trapped inside a giant ctenophore.

When the Octopod's waterworks are flooded with frightened Humuhumu fish, the Octonauts have to find a way to flush them out.

When a gigantic saltwater crocodile wanders into freezing waters, the Octonauts must figure out how to get the predator back to his warm water home - without anyone getting hurt.

While exploring the Arctic, the Octopod gets trapped in the ice. Only Barnacles's skillful navigation, and the help of a friendly Narwhal, can get them free.

When Shellington gets trapped in the middle of a massive Jellyfish bloom, it's up to the Octonauts to rescue him.

When Kwazii's Gup-B breaks down in a storm, not even brave Captain Barnacles can save him alone. Fortunately, a chain of reef lobsters lends a hand - and some claws.

When Shellington gets lost in a dark sea cave, he gets unexpected assistance from some blind Remipedes.

The Octonauts have their hands full as they look after a headstrong young Lemon Shark who's hurt his nose and can't find his way home.

Shellington and the Octonauts try to track an unusual creature: a jellyfish that can transform from old to young repeatedly - and live forever!

When all the Gups go out of control, Barnacles and Kwazii leap onto the backs of some speedy Sailfish to round them up.

Peso must gather all his courage when he travels deep down to the very bottom of the ocean, the Midnight Zone, and encounters the mysterious Vampire Squid.

The Octonauts must work together as a team to help a lost sardine find her school.

When the Octonauts all pitch in to help save a sick coral reef, they get some unexpected help from a pod of playful dolphins.

Down in the darkness of the ocean deep, Peso and the Octonauts must help a tiny, injured Dwarf Lantern Shark.

Captain Barnacles allows Tunip to use his Octo-compass. But when Tunip loses it, a cuttlefish takes it.

While Kwazii and Peso have their hands full babysitting a bunch of Adelie penguin chicks, Captain Barnacles must rescue the chicks' parents from a perilous sea storm!

Kwazii and Dashi become entangled in a strange deep-sea creature - a siphonophore.

The Octonauts head to the kelp forest to visit Shellington's sister, Pearl, and her newborn son Periwinkle - only to find the forest endangered by an infestation of kelp-eating urchins!

The Octonauts journey across a dangerous expanse of ice to help a penguin mother get back to her family.

While diving down to the Midnight Zone, the Octonauts are attacked by bomber worms.

Dashi teams up with her little sister Koshi to help the Octonauts solve a mysterious disappearance in the Kelp Forest. This is the second episode in which is unknown who sounded the Octo-Alert.