The Merman Code

S2 E17: Cam realizes the shape of the pedestal in the merman chamber is identical to Mako Island, and that five decorative inlays on the pedestal correspond to five rock outcrops on Mako reef. When Erik dives to one of the outcrops and touches it, he vanishes, transported into a sphere of endless water with no way out. Zac and the mermaids help search for Erik. In the process of freeing him, Zac discovers the key to activating the merman chamber.