Boundaries of the Ionian Sea. Red lines define the I.H.O. border.
The name Ionian comes from the Greek language Ἰόνιον (πέλαγος). Its etymology is unknown. Ancient Greek writers, especially Aeschylus, linked it to the myth of Io. In Ancient Greek the adjective Ionios (Ἰόνιος) was used as an epithet for the sea because Io swam across it. According to the Oxford Classical Dictionary, the name may derive from Ionians who sailed to the West. There were also narratives about other eponymic legendary figures; according to one version, Ionius was a son of Adrias (eponymic for the Adriatic Sea); according to another, Ionius was a son of
Dyrrhachus. When Dyrrhachus was attacked by his own brothers, Heracles, who was passing through the area, came to his aid, but in the fight the hero killed his ally's son by mistake. The body was cast into the water, and thereafter was called the Ionian Sea.