Benthesikyme or Benthesicyme (Βενθεσικύμη, from βένθος "(sea) depth" and κῦμα "wave") in Greek mythology, according to the Bibliotheca, was a daughter of Poseidon and Amphitrite and wife of Enalos, by whom she had two daughters. She raised Eumolpus, son of Chione and Poseidon.
When Chione gave birth, she was so frightened of her father's reaction that she threw the baby into the ocean. As Pseudo-Apollodorus relates:
But Poseidon picked him up and conveyed him to Ethiopia, and gave him to Benthesikyme (a daughter of his own by Amphitrite) to bring up. When she was full grown, Benthesicyme's husband gave him one of his two daughters. But he tried to force his wife's sister...Some Greeks claim that Benthesikyme had a son named Aprhonysis, but such claims can't be verified.
Accordingly, Eumolpus was sent into exile.
References
Benthesikyme Wikipedia(Text) CC BY-SA