Silly skylarking schoolgirls Cleo, Emma and Ricki get caught in a cave on 'moon island' Mako. Before they can swim away, the moon lights them up at night. Back on land, they find that each will, when wet, quickly transform temporarily into a fish-tail mermaid. They dare not tell anyone, not even nerdy tutor Lewis McCartney. Two even discover they now have a magical control over bodies of water. Written by KGF Vissers

The girls can't resist an invitation to a pool party thrown for hunky surfer Byron. However it proves impossible to prevent getting wet there, so they're rather lucky to be discovered transforming into mermaids only by Lewis, who is ready to keep their secret. Written by KGF Vissers

The girls test how long they can hold their breath as mermaids. Thus they discover that ecologist Clio's pa Don Sertori's fishing boat is catching sea turtles and sneakily cut them loose. That proves dangerous, but they do expose the real culprit, Don's foreman Eddie. Written by KGF Vissers

Cleo convinces Emma to go ahead with her traditional slumber party, with some unexpected results.

After discovering Cleo's Mermaid diary, Cleo's little sister is determined to save the Gold Coast from the 'evil Mermaids'.

When Rikki drags Elliot from the surf Emma is worried about exposure, but Rikki is more worried about the crush he's developed.

Cleo receives a mysterious warning: do not stare at the full moon, not even its reflection. Emma is more concerned about her father's surprise birthday party.

Lewis gets a job as lab assistant to the beautiful Dr Denman in an effort to find more answers for the girls, but they're not convinced he can keep their secret.

When Cleo's pet fish passes away, Rikki tries to cheer her up.

Not convinced an interview with Emma's mum will win the short film competition, Rikki decides to get some award-winning shark footage. Zane recruits Lewis to re-enact a record windsurfing run.

Byron asks Emma to coach him for the school swimming carnival. Rikki vents her frustration at Lewis's apparent disinterest in the girls as anything other than specimens.

The strange old woman warns the girls about the dangers of the full moon but Cleo falls under its spell this time; she turns into a Siren and develops a singing voice that brings half the boys in the neighborhood to her doorstep.

Emma stumbles upon the mysterious Elder who knows more about what it means to be a Mermaid than the girls themselves.

Why is Cleo so desperate to avoid celebrating her 16th birthday? Zane recruits Lewis in his hunt for the 'sea monster'.

When Emma is left in charge of the Juicenet café, Miriam is determined to make things go wrong. When she turns off the cooling system in the cold room, Emma tries to fix it by freezing everything in the room, including Miriam hiding inside! Written by Kittygirl

When Cleo drops her locket into a pool at the marine park, she meets Ronnie, the park's new dolphin. Zane researches the sea monster that rescued him. Many misinterpretations lead Cleo and Zane's loved ones to think that they are dating.

Rather than risk exposure by getting wet in a rainstorm, Emma, Cleo and Rikki decide to play sick to avoid having to go to school. However, they overdo it and when the Dr is called to check in on the girls, she becomes alarmed and alerts the CDC that there may be a dangerous contagion. Written by Anonymous

Another full moon is happening, the girls and Lewis try their best to make sure no moonlight can get in, and they succeed, until Lewis leaves. Cleo and Emma block the moon light, but Rikki sees it from a reflection in her water. Rikki loses control of her power and flees to Mako Island after being scared of hurting Cleo and Rikki. Meanwhile, Zane, being haunted by the tail he saw when he almost drowned, does some research, which leads him to Mako. He finds Rikki surrounded by fire. Feeling scared and lonely, they kiss, but Rikki ends up hurting Zane, and she doesn't remember until Zane asked her about it at the JuiceNet café, in front of Cleo. Written by Emma L, H2O super fan :D

Angela, who is Cleo and Kim's cousin, comes to town for a visit. She acts very grown up and sweet but when Cleo takes her to the amusement park with her sister, she disappears. Cleo and Kim search for her but all Cleo finds is a rather large bird in the bathtub at home. When Cleo tries to return the bird, she is caught and it is assumed she was stealing the bird instead. Written by Anonymous

Lewis' excitement about testing his new lure in the annual fishing derby is quelled by Cleo's refusal to renew their traditional partnership for fear of getting wet. When Lewis struggles, Cleo decides to use her mermaid powers help Lewis land the big one but when he is accussed of cheating, he is kicked out of the competition by Cleo's father and forbidden from seeing her again. Rikki and Zane encounter one another at a business seminar and get trapped on a balcony. The time alone together allows them to get to know one another better, perhaps a little too well when the rain starts falling. Written by H20 Home website

When Byron tells Emma she's dependable with the same look and vibe, she feels predictable and decides to change her look by dying her hair. Zane thinks Miss Chatham holds the key to identifying the sea monster he saw when he almost drowned. Written by grrlpunk

Rikki and Zane begin secretly dating but Cleo and Emma catch them together at the movies. Cleo and Emma demand that she stop seeing Zane, forcing her to choose between him and them. Rikki refuses saying that true friends would never make her choose. Written by Anonymous

Rikki and Zane see a locket in a shop window that looks just like the one Cleo found by Mako Island. Miss Chatham tells the girls how her and her friends, Julia and Gracie, were mermaids when they were 15. Miriam buys the locket to spite Rikki. Written by grrlpunk

Lewis thinks he has invented a potion to make the girls waterproof for their big dance. However, his concoction has an undesirable side effect, turning the girls bright red right in the middle of the dance.

Dr. Denman returns. Zane thinks she can help him prove his theory that there are mermaids living by Mako Island. Emma avoids her family's plan to vacation at a beach resort. SPOILER: Harrison and Dr. Denman discover the girls are mermaids.

While Dr. Denman holds Lewis prisoner on her boat, she and Harrison trap the girls in the Moon Pool. Zane must choose between his father and helping the girls. Their only chance to avoid exposure is to give up their powers. Will they do it? Written by grrlpunk