Charybdis

"Charybdis was an orthodontist's nightmare. She was nothing but a huge black maw with bad teeth alignment and a serious overbite, and she'd done nothing for centuries but eat without brushing after meals."

- Percy Jackson describing Charybdis

Charybdis was once a beautiful naiad, the daughter of Poseidon and Gaia. She takes the form of a huge mouth that swallows great amounts of water and debris three times a day, creating multiple massive whirlpools.

History
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, covering 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 forever.

The myths say that Charybdis lay on one side of a blue, 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 phrase "between Scylla and Charybdis" has come to mean being in a state where one is between two dangers and moving away from one will cause you to be in danger of the other. It is the origin of the phrase "between the rock and the whirlpool"-the rock upon which Scylla dwelt and the whirlpool of Charybdis-and may also be the genesis of the phrase "between a rock and a hard place."

Odysseus had to sail between her and Scylla while trying to return home.

The Sea of Monsters
Clarisse La Rue takes her ironclad between Charybdis and Scylla to enter the Sea of Monsters, which is located in the Bermuda Triangle. Clarisse decides to sail closer to Charybdis because she feels that her ship's cannons will be enough to destroy Charybdis and send her to Tartarus. In fact, Clarisse purposely faces Charybdis and Scylla because she wants the chance to destroy monsters, much to Annabeth and Percy's chagrin.

As the group gets pulled closer to the whirlpool, Percy tried to control the waves, but the roar and strength of Charybdis is overpowering and Percy is unable to control the water. When they are in range, Clarisse orders her undead soldiers to fire and three shots hit Charybdis with no effect at all. When Tyson fixes the engines and they start to pull away, Clarisse orders them to stay close so they can keep firing. Before they can, Charybdis closes her mouth and the water covers her. She then releases a blast of water that causes the CSS Birmingham to go out of control and heavily damaged as the hull cracks. Even one of the cannonballs that Clarisse had fired is shot back and hits her ship. It is quickly discovered that the wave of water caused Clarisse's ship to sail too close to Scylla and one of her undead crew members is eaten right off the deck.

Appearance
The mouth of Charybdis is surrounded by mist, smoke, and water. She anchors herself to a black reef, with a small fig tree on top. Charybdis herself has slimy lips and mossy teeth, each tooth being about the size of a rowboat. Her teeth are also covered in bands of corroded metal (similar to braces), with pieces of fish, driftwood, and floating garbage stuck between them. Her mouth is nothing but a huge black maw with bad teeth alignment and a serious overbite.

Abilities
Charybdis is able to suck in large amounts of water like a whirlpool, and then releases it in a blast that can destroy everything within a half mile. When pulling in water, she will suck in anything nearby, including sharks, schools of fish, and giant squids. If a ship gets to close to her, they will be pulled in by the whirlpool she forms or destroyed by the blast that follows.

Trivia

 * Charybdis is Percy's half-sister, as they are both children of Poseidon.
 * Scylla and Charybdis may refer to the space between Siciliy and Italy, where sea currents are very strong.
 * The expression "between Scylla and Charybdis," between two tough situations, has come from this myth.
 * The CSS Birmingham firing at Charybdis is one of the images Tyson engraved on Percy's wristwatch shield