2019 3 oz POSEIDON Silver Coin MS 70 Gods of the World – Cook Islands. Poseidon was one of the Twelve Olympians in ancient Greek religion and myth. He was god of the sea and other waters, of earthquakes, and of horses. In pre-Olympian Bronze Age Greece, he was venerated as a chief deity at Pylos and Thebes. Poseidon was protector of seafarers, and of many Hellenic cities and colonies. In Homer’s Iliad, Poseidon supports the Greeks against the Trojans during the Trojan War. In the Odyssey, during the sea-voyage from Troy back home to Ithaca, the Greek hero Odysseus provokes Poseidon’s fury by blinding his son the Cyclops Polyphemus. Poseidon is also the subject of a Homeric hymn. In Plato’s Timaeus and Critias, the island of Atlantis was Poseidon’s domain.