Opheltes was the son of the Nemean king Lycurgus and his wife Eurydice. He became a well-known hero for his tragic fate, which was caused by his nurse Hypsipyle.
Hypsipyle, who was previously the queen of the island Lemnos, was a slave of Lycurgus in charge of his son Opheltes. One day, when she was walking in the meadows with Opheltes in her arms, she met the seven Argive generals in their march against Thebes. They asked her to show a water-spring for lest their thirst. Hypsipyle put the child in the grass where wild celery was growing, and guided them to a spring hidden in the forest. During her absence a large snake came out from the brushes and crawled around Opheltes neck, strangling him. The soldiers and Hypsipyle returned too late, and found the boy already dead. Lycurgus wanted to kill Hypsipyle but one of the soldiers protected her against his anger.
After this incident the generals held a funeral celebration for Opheltes and they arranged sport games to honor him. According to one myth this was the beginning of the famous Nemean Games, but another story tells us that the founder of the Nemean Games was Heracles. The price for the winners of these games was a crown of wild celery, which later on became the symbol of sadness for Opheltes.
It was said that the grave of Opheltes was located in the archaic underground crypt, situated under one of the corners of the temple of Zeus in Nemea. Pausanias even describes a place (near the temple, at a grove of cypresses), where Opheltes was killed by the snake. In later times Opheltes was worshiped there as a hero and they called him after his death Archemorus (from Greek words archí, "old" and morós, "fate, a lot, a destruction or death").