In Greek mythology, Kharybdis or Charybdis was a sea monster, the daughter of Poseidon and Gaia. She takes form as a monstrous mouth and swallows huge amounts of water three times a day before belching them back out again, creating whirlpools. Charybdis was originally a naiad, sea-nymph who stole Heracles' cattle until Zeus became angry, threw her into the sea and, as punishment, turned her into a sea monster.
Charybdis is a whirlpool that sucks down water three times a day and then spews it back up three times a day. It is situated near Scylla, a six-headed monster that lives in a gray rock. Odysseus and his men must sail between these two dangers. Since the entire crew would perish if the ship were sucked down by Charybdis, Circe advises Odysseus to steer closer to Scylla because he will lose only six men to this monster. Although Odysseus doesn't like either choice (metaphorically, he is "between a rock and a hard place"), he chooses Scylla.
Later after his men break the rules and eat some of the Sun-god's sacred cattle, Zeus creates a storm that drives the ship into Charybdis. The whole crew is sucked down into the whirlpool and drowns. Only Odysseus, who manages to grab the fig tree and save himself from the whirlpool, survives.
Charybdis in the Odyssey is a deep whirlpool made by Poseidon for revenge.