Caribdis (Greek: Χάρυβδις), in Greek mythology, was a sea creature protective of territorial boundaries at sea. In another tradition, it would be a whirlpool created by Posidon.
In older times, Caribdis was more closely linked to legends of sailors and fishermen than properly to Greek mythology. Homer positioned her as a mythological entity, taking her from simple regional legend. Homer called her "the divine Caribdis," using the same adjective applied to the beautiful cave nymph, Calypso.
During her existence as a nymph, Charybdis was characterized by extreme voracity. When Heracles passed near Messina, taking Geryon's oxen, she stole some of the animals and devoured them.
Trying to invest against the hero, who was trying to recover his cattle, Caribdis was fulminated by Zeus with a thunderbolt, and thrown into the depths of the sea, where she was transformed into a sea monster.
In Greek mythological tradition, Charybdis was usually related to Scylla, another sea monster. The two lived on opposite sides of the Strait of Messina, which separates the Italian peninsula from Sicily, and personified the dangers of sailing near rocks and whirlpools.
On top of the cliff, which was not as high as the opposite cliff of Scylla, stood a black fig tree. Charybdis herself was out of sight. Three times a day he would sip the waters of the sea and three times a day he would spit them out again.
When Odysseus passed through the Strait of Messina, he was swept away by the whirlpool of Caribdis, after a shipwreck caused by the sacrilege committed against Helios' oxen.
He managed, however, to cling to the fig tree that stood in front of the monster's cave and then cling to a mast of the wrecked ship, managing to escape and continue his journey.