Category:Cast


 * Lucy Fry as Lyla (series 1), seen as the leader of the three mermaids. She is hot-headed, determined, but still very smart. Despite initially only being interested in him for the sake of removing his powers, she develops an attachment to Zac. She and Nixie are with the pod in season 2.
 * Ivy Latimer as Nixie (series 1), one of the three mermaids. She is an adventurous girl, who often gets into trouble and only does what she believes is right. In series 2, it is explained that she and Lyla have left to search for a new home for the mermaid pod.
 * Amy Ruffle as Sirena (series 1–2), one of the three mermaids. Naive and sweet, she acts as a mediator and peacemaker when Lyla and Nixie quarrel.
 * Chai Romruen as Zac, who becomes a merman after falling into the Moon Pool during a full moon while camping on Mako Island. He grew up surfing and is sporty. In series 2, he discovers that he was born a merman and that Mimmi is his sister.
 * Isabel Durant as Ondina (series 2–3),[3][4] a mermaid who works to remove Zac's powers. She is headstrong and tries to do things her way.
 * Allie Bertram as Mimmi (series 2–3),[3][4] a mermaid who works to remove Zac's powers. She is intelligent and inquisitive, and occasionally has to bail Ondina out of trouble. She eventually finds out that Zac is her long lost brother.
 * Gemma Forsyth as Evie (recurring, series 1; main, series 2–3), who is Zac's girlfriend. In series one, she believes the girls are stalking her and is jealous of Zac spending time with Lyla. She eventually learns the girls are mermaids and apologises for her quick judgement. She is accidentally transformed into a mermaid in series two and back into a land girl again in series three.
 * Alex Cubis as Erik (series 2),[3] a merman who is descended from a line of mermen who have not been seen for thousands of years. He is solitary and elusive.
 * Linda Ngo as Weilan (series 3),[4] a Chinese mermaid who accidentally leads a magic water dragon to Mako. She is sassy and has a dry wit. She prefers sleeping and socialising on land as the dragon has caused her to be wary of life in the ocean.
 * Dominic Deutscher as Cam, Zac's best friend who quickly becomes aware of Zac's transformation into a merman. While Cam is initially supportive of his friend and helps to keep his secret, he becomes jealous and envious of Zac's powers. He is outraged when Zac tries to return the trident to its chamber, and works to become a merman himself. They later make up and Cam helps Zac destroy the merman chamber.
 * Kerith Atkinson as Rita, the school principal and a mermaid. She left her pod years ago to be with a human boy she fell in love with, but who died before they could marry. She serves as a source of knowledge and history for the girls, and teaches them how to properly use their powers.
 * Rowan Hills as David, an employee at the Ocean Cafe. He and Sirena become mutual love interests. David finds out about mermaids at the end of series 2.
 * Brooke Lee as Carly, an employee at the Ocean Cafe. She had feelings for David but is now with Cam. She is also Evie's best friend, and later finds out about mermaids in series 2.