The Styx is a river located in Arcadia, central Peloponnese, Greece, known for its dramatic descent from a snow-fed spring and flowing through a rugged gorge before merging with the Crathis River. The name "Styx," meaning "hateful," reflects the river's legendary properties; it was believed that its waters were so toxic they could dissolve any vessel, except those made from a horse's hoof. In historical accounts, such as those by Herodotus, the river held significant cultural relevance, as it was used for solemn oaths, exemplified by King Cleomenes I of Sparta, who required members of his league to swear by it.

The Styx is also deeply entrenched in mythology, identified during the classical era as one of the nine rivers in the Greek underworld. It features prominently in the works of poets like Homer and Hesiod, with gods swearing by its waters, which could render a perjurer senseless for an entire year. In Hesiod's works, Styx is personified as a goddess and is portrayed as the daughter of Ocean, playing a key role in the divine conflict involving Zeus and Cronos. The river's rich mythological and historical background makes it a fascinating subject for those interested in ancient Greek culture and literature.