The year is 2020. Fifteen-year-old Noah lives with his family in the futuristic underground community of North Col. The world above is a frozen wasteland after a massive comet strike destroyed all other life in the world including the animals. One night, he accidentally time travels to the future and finds himself trapped in the year 2085 in a desolate desert place called Haven with a group of children, the Nomads, led by Arushka.

When a spaceship carrying pretty, teen aliens Zoey and Kiki lands in the quiet Australian surf town of Lightning Point, the girls have to befriend local surfiegirl Amber and let her in on their secret. But while the duo learns about Earth, surf and falling in love, the girls soon realize that they aren’t the first extraterrestrial visitors.

When ordinary teenager Kyra touches a mysterious book, she is transformed into a Tri-ling-–part-human, part-fairy and part-elf. In addition to acquiring amazing magical powers, Kyra discovers a secret world of magic all around her.

Real-life mermaids, Sirena, Nixie and Lyla are part of a mermaid pod, which lives in the waters of Mako Island. As young members of the pod, it is their job to protect the Moon Pool and guard it from trespassers. But on the night of a full moon, the mischievous mermaid girls neglect their duties. Sixteen-year-old land-dweller Zac enters the Moon Pool and forms a special connection with Mako.

Zac is given a fish-like tail and amazing powers. The mermaid pod is forced to leave Mako, leaving behind the three mermaid girls, cast out of the pod. They know there’s only one way they will be allowed to rejoin the pod: They must get legs, venture onto land and take back Zac’s powers – or risk being outcasts forever.

H2O: Just Add Water revolves around three teenage girls facing everyday teen problems with an added twist: they cope with the burden of growing a giant fin and transforming into mermaids whenever they come in contact with water.