When the Pups and Cap'n Turbot camp out under the very rare Magical Mer Moon, magical things begin to happen. Lured by the mystical Mer pup song and then transformed into Mer pups themselves, Skye and Zuma and even water resistant Rocky perform an underwater rescue in a sunken old ship. Cap'n Turbot and Ryder help out by diving deep to bottom of the Bay in their Diving Bell to help a Mer Mom and pup.