Cleo and Rikki face their final year of high school without Emma. They make a new friend in Bella and meet new boy Will – and encounter a strange new force on Mako Island that turns water against them.
Cleo's forced to put Lewis' plans for romance on hold to restrain Kim's out of control love life. During this Don meets Samantha, a National Parks Manager and they start to date.
Zane concocts a dirt bike race to publicise the cafe. When Rikki discovers it's a scam she and Bella decide to teach him and Nate a lesson. Cleo and Lewis make a big discovery about mixing the waters in the Moon Pool.
Rikki and Bella hide out at Cleo's to protect themselves from a full moon water attack. Bella's kidnapped by a water tentacle and taken to Mako Island. Lewis tries to keep Will away from the island so the girls can rescue her.
A problematic family beach picnic leads Don to end his relationship with Samantha until Cleo encourages him to pursue it. Will's sister Sophie competes with Bella for a job at the cafe and sets her sights on Zane.
