Charybdis and her sister Scylla were evil spirits of the seas and daughters of Poseidon, the major Greek god of the Seas and Gaea, the goddess of the Earth.
The two sisters were living together on either sides of the island of Sicily in Italy, spreading fear among the sailors crossing the island.
Charybdis' particular task was to swallow water three times a day and then throw up, creating this way whirlpools in order to drown vessels that passed by.
Scylla and Charybdis are mostly mentioned in Homer's famous Epos, the "Odyssey".