## The River Styx is one of the five rivers of the Greek Underworld, rivers that separate Hades from the land of the living.
During the Titanomachy (the Titan war), which was fought between the Titans) and the Olympians, the goddess Styx sided with the Olympians.
Once the war was won, Zeus, king of the Olympians, promised that every oath be sworn on Styx's name, as a sign of the greatest respect.
He also proceeded to name the River Styx after her.
Achilles was dipped in it as a child and was rewarded with invulnerability, except for his heel, which was where his mother was holding him, hence the term : Achilles' heel.
The full list of rivers surrounding Hades :
1. Acheron \- the river of woe
2. Cocytus \- the river of lamentation
3. Phlegethon \- the river of fire
4. Lethe \- the river of forgetfulness
5. Styx \- the river of hate