Poseidon, the sea god of Ancient Greece, was incredibly powerful. He had control over the ocean, and could use this to punish those on his bad side. With only a tap of his trident, a mighty earthquake would form.
To avoid a cruel punishment, Greek sailors would pray to Poseidon and offer sacrifices. Greek musicians and athletes would also compete in the Isthmian Games. Victors would receive a crown of dried wild celery leaves, a plant sacred to Poseidon.
Despite all of his power, Poseidon was often jealous of other gods and goddesses. The king of the Athens held a competition to see which god would have the most power over the land. Athena won, and Poseidon was very displeased. He fought with Hera over Argolis, and when he lost, he dried out the land's three main rivers. He argued with Zeus over Aegina, and Dionysus over Naxos. He continued to be unsuccessful, and remained envious of the other's possessions.