Ant and Fontaine realise that 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?

Ant and Fontaine discover the secret of the Bajau Laut people, a tribe of sea nomads living in the South China Sea. The pair are determined to help them - but how do you find a fish that walks?

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?

The Nektons are busy recovering sunken shipping containers, so when Bethany the fish finds herself in danger, only Jeffrey can save her.

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?

Mad Madeline steals the dangerous Sceptre of Queen Dorius.

Ant has created a clever machine to clean up a vast oceanic rubbish dump. However, when the machine is been eaten by a huge creature, it's up to the Nektons to save it.

Fontaine is amazed when Smiling Finn tells her that he has detected a signal from her grandparents’ missing submarine. Is this a joke, an elaborate scam, or something even more amazing?

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.

The Nektons help locate a legendary Singaporean glass cabinet. However, they discover it is guarded by a terrifying and familiar creature.

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?

A submarine is trapped in an astonishing location. The Nektons launch an elaborate and dangerous rescue mission to save the people inside. Could it be their missing grandparents?

A mysterious dolphin in a sophisticated electronic harness zaps all the Rover's power. Ant and Fontaine manage to remove the harness, but can they rehabilitate this cybernetic dolphin to survive in the wild?

The Nektons find the Queen's sceptre. But faced with the Kraken and the Electric Ray Monumential together, can Ant make it work?

The Dark Orca pirates unwittingly steal a treasure that could awaken a Monumential.

The Internet being down is the worst thing imaginable for Ant and Fontaine - until Ant finds the sea monster responsible for this. Can he save both?

Trying to rescue Jess Gorman in an underwater cave proves dangerous for Ant and Fontaine until a manatee comes to their aid. But is it too late?

The Aronnax and Alpheus's sub are trapped within a giant jellyfish. They've been eaten and the jellyfish won't let food out.

Devil Daniels insists he's relocating a dangerous killer whale. But it's a scam that turns dangerous. Our heroes need to save Ant and the whale.

The Nektons find an amazing underwater crop circle. It's been built by a giant male puffer fish to attract a mate. Can Ant help the romance along?

Ant tries to locate a 'diamond-horned sea-unicorn' as a present for Fontaine's birthday. But Dolos and Devil Daniels are also hunting it.

The Nektons try to save an island from the 'purple tide' that legend says will destroy everything. To save it, they need to locate the Protector.

Ant wants to go faster than the fastest fish in the sea - the sailfish. But he hasn't counted on a deadly oil spill that threatens to destroy them.

Jeffrey is kidnapped, in his 'Jeffrey Knight', by Dark Orca pirates. Can Jeffrey turn the tables and save himself?

The Rover is swallowed by a huge prehistoric shark. Will and Fontaine manage to cling to its gills just inside its mouth.