Poseidon or Posidon is one of the twelve Olympian deities of the pantheon in Greek mythology. His main domain is the ocean, and he is called the "God of the Sea". Additionally, he is referred to as "Earth-Shaker" due to his role in causing earthquakes, and has been called the "tamer of horses".
…a general tradition attributes the function of god of the seas to Poseidon, although he is a god of many powers, wider-ranging than a simple marine deity. The origin of this complexity has been sought in prehistoric times, and it has been shown that the attributes of several ancient divinities were probably based upon his personality.
There are various theories about the origins of Poseidon. The god was worshiped as Poseidon Heliconius by the Ionians, a race of people who migrated from mainland Greece to western Asia around 1000 BCE. Some scholars have suggested that, if this mane was derived from that of Mount HElicon in Boeotia, Poseidon might originally have been a sky god. Poseidon's characteristic trident, or three-pointed spear, could once have been a thunderbolt. The god's connection with bulls and horses, on the other hand, suggests an association with fertility.
The worship of Poseidon extended across the Greek lands and eventually made its way into Rome under the guise of King Neptune. He was equated with many islands including Crete, Chios, Delos and Cos, as well as numerous seaports and the Isthmus of Corinth. His cult was alive in Delphi and throughout northern Boeotia, and he was also celebrated in Attica before Athens became recognized as such an important sea power.
[Poseidon] was widely worshipped in ancient Greece, with numerous temples and shrines. The foremost of these were his sanctuary near Korinthos, where the famed Isthmian Games were celebrated in his honour every four years, and the shrines at Helike in Akhaia, and Onkhestos in Boiotia.
in Homer, Poseidon though a mighty force, is mostly a vindictive one. He is an alien. He stands always for Crete and Cretan civilization, a civilization in some ways as great as that of Greece, and which contributed much to Hellenic culture, but which was not Hellenic, and could never wholly be assimilated by Greece. The Minoans were not a people of artists. With all their costly material and skill in handicraft, they lacked that austerity, that reserve, that instinct for clean beauty, which was the birthright of the Hellene.
A defining moment of Poseidon’s godly career was when he lost the battle of Athens to none other than the Goddess Athena. Although initially ashamed and enraged by his loss, he eventually ended up cooperating and collaborating with Athena (well at least for the most part). She was even the one who actually build the first ship that sailed over the sea, Poseidon’s territory
...Poseidon set out to find a wife. On his way, he stumbled upon the mermaid Amphitrite, a sea nymph with golden hair and shimmering blue eyes, dancing on the island of Naxos with her girlfriends. Captured by her extraordinary beauty, Poseidon couldn't help falling in love with her and asked her to marry him. [...] Poseidon was determined. So he sent his messenger Delphinus, the king of the dolphins, to locate the mermaid and win her heart. The dolphin king obeyed and started a long, perilous journey to find the love of his master. When he finally located the maid, he promissed her that, if she married Poseidon, all the energies of Poseidon would balance and tranquility would come to the world of waters. No strong sea would ever do harm to the seamen again. Touched with emotion, Amphitrite surrendered and she married Poseidon.
Poseidon was essentially the presiding deity over fishermen, and was on that account, more particularly worshipped and revered in countries bordering on the sea-coast, where fish naturally formed a staple commodity of trade. He was supposed to vent his displeasure by sending disastrous inundations, which completely destroyed whole countries, and were usually accompanied by terrible marine monsters, who swallowed up and devoured those whom the floods had spared. It is probable that these sea-monsters are the poetical figures which represent the demons of hunger and famine, necessarily accompanying a general inundation.
Appropriately, Poseidon, Greek god of the sea, was most often depicted riding atop the ocean waves, sometimes on his chariot pulled by seahorses. He was almost always shown holding his signature weapon, the trident, which is often used by humans as a fishing spear.
Originally, Poseidon was the god of water, but later became a sea-god as well as the ultimate master of the wells and rivers. His temples were usually situated by the sea, the remains of one of them can still be seen at Cap Sounion, not far from Athens
Poseidon is the son of Kronos (Cronos) and Rheia, brother of Zeus, Hades, Hestia, Demeter and Hera. He is one of the six original Olympians. His mission is to give voice to the earth. Poseidon was commonly called the Earth-Shaker and the Earth-Encircler in the Iliad and the Odyssey of Homer. He pounds and shakes the earth and sea with his wrath and pleasure and answers to no one, except Zeus. His kingdom is the vast sea which he has populated with creatures of his own design. He rides the waves in a chariot drawn by dolphins but, curiously enough, his most honored creation is the horse.