What whirlpool monster is opposite Scylla?

What whirlpool monster is opposite Scylla? Charybdis is the whirlpool monster positioned opposite Scylla in Greek mythology. Together, they guard a narrow sea passage that Odysseus must navigate during his return voyage to Ithaca.

In Homer's Odyssey, Charybdis swallows enormous quantities of seawater three times a day and then regurgitates it, creating a deadly whirlpool. Scylla lives on the opposing rock and attacks passing ships with her six heads. Circe warns Odysseus that he must choose which danger to approach, and he steers nearer to Scylla because Charybdis could destroy the entire ship.

The pair became the source of the expression “between Scylla and Charybdis,” meaning a choice between two serious dangers. Ancient writers placed the monsters in the Strait of Messina, between Sicily and the Italian mainland. The real strait does experience powerful currents and whirlpools, although modern conditions are not comparable to the supernatural hazards described in epic poetry. Charybdis is therefore both a monster and, in some versions, the whirlpool itself.