Cleo discovers a comet is causing fish to flee the waters around Mako Island. The girls find a way to restart the message in the Moon Pool and discover the comet will collide with earth. Sophie meets Ryan and with Zane's help they join forces to remove the crystals from the Moon Pool.
Elenco: Cariba Heine , Phoebe Tonkin , Angus McLaren , Cleo Massey , Burgess Abernethy , Indiana Evans , Alan David Lee , Jamie Timony , Luke Mitchell , Craig Horner , Taryn Marler , Trent Sullivan , Caroline Kennison .