The third series is scheduled for broadcast in 2009. The series centres around Cleo and Rikki coming to terms with the loss of Emma, who has left town with her family. New characters are introduced, including Bella, a new mermaid who infuses the group with new energy; and Will, a skilled diver who accidentally unleashes a powerful force from Mako Island which turns water against the mermaids. The girls must also deal with Zane, who attempts to exploit Mako's secrets after Rikki breaks up with him.