Marina takes the viewer on the fairy-tale adventures of the mermaid "Marina". Born as Cristina to human parents Esther and Elias, Marina falls victim to a curse by Victoria, a sea deity disguised as a normal woman. Seeking vengeance on Elias, who spurned her love and married Esther, Victoria cursed their daughter. In the hopes that Victoria would lift her curse on the child, Elias leaves Esther but eventually falls into insanity. Esther, on the other hand, was left to raise Cristina alone. When the curse came true and the child turned into a mermaid on her seventh birthday, Esther realized that Cristina's life would be endangered in their superstitious fishing village, where mermaids are believed to be unlucky. As such, Esther is forced to release Cristina in the sea, where she is found and cared for by the mermaids headed by "Istah", their beauteous queen.