Plot

A young man is magically turned a merman, and discovers his underwater origins, after he comes in contact with the magic waters at the mysterious Mako Island guarded by a trio of mermaids.

During a trip to Mako Island, Zac gets in touch with the water of the magic Moon Pool in a night of full Moon, gaining a merman tail and the power to manipulate water. Sirena, Nixie and Lyla, three mermaids who guard Mako Island, are sent to mainland by their fellow mermaids to deprive Zac of his powers, otherwise they will be forever banned from the island.—EliOrni

Mako Island is protected by a pod of mermaids, during the full moon it's the job of Lyla, Nixie and Sirena, but things don't go to plan. Land boy Zac Blakely falls into the sacred mermaid Moon Pool gaining a tail and powers.

Mako Mermaids centers on three mermaids, Sirena, Nixie, and Lyla, who are assigned with the task of protecting their magical Mako Island from trespassers, only to be thwarted by the arrival of a 16 year old land-dweller Zac - who forms a special connection with the island and is granted a blue fish-like tail and amazing marine powers. Threatened by his existence, the mermaid pod are forced to move away, abandoning Sirena, Nixie, and Lyla, who in a bid for survival must get legs, venture onto land, and take back Zac's powers or risk being outcasts forever.

When 15-year-old Zac goes camping on Mako Island, he has no idea his every move is being monitored by real-life mermaids Sirena, Nixie and Lyla, whose job it is to ward off trespassers. When he comes into contact with the magical waters of the Moon Pool on the night of a full moon, Zac is given a taste of Mako's powers, waking the next day to discover he has been granted fin-like feet and the power to control water - causing all sorts of trouble for Sirena, Nixie and Lyla.