In the Twelve Labors of Hercules, Geryon kept his cattle on the island of Erytheia.
Eurystheus sent Hercules to bring back the red cattle of Geryon, a formidable being described in many traditions as having three bodies or three joined forms. The herd was guarded by the herdsman Eurytion and the two-headed hound Orthrus.
Erytheia was placed in the far western regions of the mythic world, often near the Atlantic Ocean. To reach it, Hercules crossed the ocean in the golden cup associated with the sun god Helios, a detail that distinguishes this journey from an ordinary voyage.
The location is sometimes translated or described differently because ancient geography treated the western edge of the world imaginatively. Erytheia, however, is the standard name for the island in accounts of the labor.