h2o: just add water

Lewis McCartney

Lewis McCartney is a character in the Nickelodeon series, H2O: Just Add Water. He is the dorky, yet loyal friend of Emma, Cleo, and Rikki. When he discovers the girls are secretly mermaids, he does everything he can to help them. His favorite activities are fishing and conducting scientific research. Later in the series, Cleo and Lewis pursue a romantic relationship.

Rikki Chadwick

Rikki Chadwick is one of the three main characters in Nickelodeon’s H2O: Just Add Water. The series takes place on the Gold Coast of Australia. A strange encounter with the magical moonpool on Mako Island turns the girls into mermaids! Now Emma, Cleo, and Rikki must navigate life as a human on land and mermaid in the water. Rikki is the rebellious tomboy of the group, but she can sometimes act feisty. Her mermaid power is boiling water. Cariba Heine portrays this character in all three seasons, and returns for a cameo in the spinoff, Mako Mermaids.

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Cleo Sertori

Cleo Sertori is one of the three main characters in Nickelodeon’s H2O: Just Add Water. The series takes place on the Gold Coast of Australia. A strange encounter with the magical moonpool on Mako Island turns the girls into mermaids! Now Emma, Cleo, and Rikki must navigate life as a human on land and mermaid in the water. Cleo is the kind-hearted one of the group, though she can be anxious. Her mermaid power is manipulating water. Phoebe Tonkin, known for her later role in The Originals, portrayed this character in all three seasons.

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Emma Gilbert

Emma Gilbert is one of the three main characters in Nickelodeon’s H2O: Just Add Water. The series takes place on the Gold Coast of Australia. A strange encounter with the magical moonpool on Mako Island turns the girls into mermaids! Now Emma, Cleo, and Rikki must navigate life as a human on land and mermaid in the water. Emma is the responsible one of the group, though she can sometimes act bossy. Her mermaid power is freezing water. Claire Holt, known for her later role in The Vampire Diaries, portrayed this character in the first two seasons.