Despina is most likely the daughter of Poseidon and Demeter. She is the Piscean Ocean Goddess, but still related to Greek Myth. She is not a mermaid, but can breathe underwater.
Despina is described as being nude, and is not wearing any clothes, but she occasionally arises from the shore and lies on flat rocks. She is also very slender, and doesn't eat much.
She misses her stay on Mount Olympus, but survives just fine by herself in the ocean.
Since Poseidon is the major god of the sea, she is a minor, and she does not necessarily rule the oceans, unlike Amphitrite. Her be-lated mother, but her mother is Demeter.
Despina's official Greek name is Δεσποινη.