Charybdis from the movie
In Greek mythology, Charybdis or Kharybdis was once a beautiful naiad and the daughter of Poseidon and Gaia. She takes form as a huge bladder of a creature whose face was all mouth and whose arms and legs were flippers and who swallows huge amounts of water three times a day before belching them back out again, creating whirlpools. In some variations of the tale, Charybdis is just a large whirlpool rather than a sea monster. Charybdis was very loyal to her father in his endless feud with Zeus; it was she who rode the hungry tides after Poseidon had stirred up a storm, and led them onto the beaches, gobbling up whole villages, submerging fields, drowning forests, claiming them for the sea. She won so much land for her father's kingdom that Zeus became enraged and changed her into a monster.
The myth has Charybdis lying on one side of a narrow channel of water. On the other side of the strait was Scylla, another sea-monster. The two sides of the strait are within an arrow's range of each other, so close that sailors attempting to avoid Charybdis will pass too close to Scylla and vice versa. The idiom 'between Scylla and Charybdis' has therefore come to mean being between two dangers, choosing either of which will bring harm. Traditionally, the location of Charybdis has been associated with the Strait of Messina off the coast of Sicily and opposite the rock on the Italian mainland identified with Scylla. The vortex there is caused by the meeting of currents but is seldom dangerous.