A submarine is trapped! The Nektons launch an elaborate and dangerous rescue mission.

Fontaine's amazed when a signal is detected from her Grandparents' missing submarine.

Ant and Fontaine rescue a polar bear from the middle of the ocean. However, when they bring her onboard, they realize she is close to giving birth! Can the Nektons move her to a safer place in time?

The Bajau Laut people are hiding a secret, Ant and Fontaine are determined to help them.

A huge creature eats a machine Ant created to clean a vast oceanic rubbish dump.

Jeffrey must dive to the rescue to save Devil Daniels and his pet fish-Bethany.

The Nektons help locate a legendary glass cabinet guarded by a terrifying creature!

Mad Madeline steals the dangerous Sceptre of Queen Dorius!

A mysterious dolphin in a strange electronic harness zaps all the power from the Rover!

Does Dolos really have a lead on finding Ant's grandparents? Or is he leading the Nektons into a dangerous chasm between moving tectonic plates for nefarious purposes?

Three baby Monumential turtles hatch, and they are the size of city blocks! The playful babies accidentally sink a fishing trawler! Can the Nektons wrangle these creatures before they sink even more ships?

Ant searches a deep chasm for clues to his grandparents' fate, but is stunned to find Mad Madeline there! She has been looking for the biggest sunken treasure ever, but all she has managed to find is the biggest monster!

Ant and Fontaine realise their grandparents found Lemuria before them - but where are they now? The Nektons follow the trail they left but run into giant, predatory Sand Strikers! Was this the fate of their grandparents?