Charybdis was a sea monster in Greek mythology, which dwelt in the Strait of Messina. It was later rationalised as a whirlpool.
It was believed that Charybdis lived under a rock on one side of the strait. Opposite Charybdis, Ancient Greeks believed there was another sea monster, Scylla, which lived inside a rock. Since the passage between the two monsters was very narrow, sailors who tried to avoid one sea monster would unavoidable get into reach of the other. Charybdis swallowed large amounts of water and then belched them out, creating large whirlpools that resulted in the destruction of passing ships. Charybdis was considered the offspring of Poseidon and Gaea, serving her father and helping him in his quarrel against Zeus. Zeus became angry that Charybdis had flooded large areas of land with water, so he turned her into a monster that would eternally swallow sea water, creating whirlpools. Charybdis was mentioned in two myths, Homer's Odyssey and Jason and the Argonauts.