Hey people! I was on wikipedia looking for news on season 3 an I found this.
The third series is scheduled for broadcast in 2009. This 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 (Indiana Evans), a singer and mermaid since the age of eight; and Will (Luke Mitchell), a skilled diver who is trying to figure out the secrets of Mako Island, and who accidentally unleashes a powerful force 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.