Geryon one of the strongest creatures alive kept beautiful cattle of red cows on the island of Cadiz off the coast of spain.
Hercules had to steal the cattle and to do so he was given enormous golden goblet shaped like water-lily, and then made for his trip across to the island.
Landing on the island Hercules was met immediately by Geryon. Each of Geryon's bodies were well covered with armour so Hercules shot each of them square in the eye. Then one by one they fell limp.
Once Hercules defeated Geryon he herded the cattle into his giant goblet and took them to the mainland. From there his progress was unimpeded until Hera sent a huge gadfly to stampede the herd in all directions.
With great difficulty Hercules rounded up all the cows and brought them to Eurystheus.