Why does Odysseus go to the underworld?

Odysseus goes to the underworld in The Odyssey because Circe tells him he must consult the ghost of Tiresias, a blind prophet, to learn how to get home to Ithaca.

After Odysseus and his men spend a year on Circe’s island, the crew grows restless and reminds him that they need to continue their homeward journey. Circe then explains that the way forward requires a descent to the underworld. She gives Odysseus detailed ritual instructions: he must find the meeting place of the rivers, dig a trench, pour offerings for the dead, sacrifice animals, and keep the shades away from the blood until Tiresias appears.

Tiresias gives Odysseus the crucial warning that shapes the rest of his voyage. He explains that Poseidon is still angry because Odysseus blinded Polyphemus, Poseidon’s son. He also warns that Odysseus and his crew can still reach home if they control themselves and do not harm the Cattle of the Sun: “Even so, you and your crew may still reach home, suffering all the way, if you only have the power to curb their wild desire and curb your own.” Tiresias adds that if the men kill the cattle, Odysseus will survive alone, and that even after returning to Ithaca he must make another journey and sacrifice to Poseidon.

The journey also deepens Odysseus’s longing for home. He meets his dead mother, Anticleia, and learns that Penelope still waits, Telemachus still holds the estate, Laertes lives in grief, and Anticleia herself died longing for him. The underworld gives Odysseus practical knowledge, but it also turns his mind more fully from wandering and glory toward home, family, and the painful duties still ahead.