What river does the Greek dead have to cross as part of their journey to the afterlife?

In Greek mythology, the river that the dead must cross to reach the afterlife is the Styx. This river is significant because it is believed to form the boundary between Earth and the Underworld. Souls of the deceased were transported across the Styx by Charon, the ferryman, who required payment for his services, often in the form of an obol (a small coin) placed in the mouth of the deceased. This practice underscores the belief that proper burial customs—including payment to Charon—are essential for ensuring that souls could safely navigate to the afterlife.

The other rivers mentioned, such as the Nile, Jordan, and Lethe, have their own mythological and cultural significance but do not serve the same function in Greek beliefs about the afterlife. The Lethe, for example, is associated with forgetfulness and oblivion, where souls drink its waters to forget their earthly lives before reincarnation. However, it is specifically the Styx that is central to the journey of the dead in Greek lore, making it the correct answer.