Poseidon, according to Greek mythology was the god of the sea, earthquakes, and horses. He also held his own appointed position among the great gods on Olympus. Although he was officially one of the supreme gods of Mount Olympus, he spent most of his time in his watery domain. He was master not only of the sea but also of the lakes and rivers. In a sense the earth belonged to him, since his waters sustained it and he could shake it at will.
He was the son of the Titans Cronus and Rhea, and the brother of Zeus and Hades. Poseidon was the husband of Amphitrite, who was one of the Nereids. They had son who they named Triton. Poseidon also had numerous other lo ve affairs especially with nyps of spring and fountains. He was the father of several children famed for their cruelty and wildness, among them the giant Orion and the Cyclops Polyphumy Poseidon and the Gorgon Medusa were the parents of the famous winged horse, Pegasus.
Poseidon was a national god of the Ionians of the Peloponnese, who brought him with them when they immigrated from Asia, and was particularly worshipped in this part of Greece. In Spart a he was even called Genethlios meaning the creator. His worship was spread throughout Greece, especially in maritime towns. The horse, the symbol of gushing springs, and the bull were sacred animals to Poseidon. In classical artwork, Poseidon very much resembles Zeus. He has a similar majesty with his bare chest, grasping his trident. He also has a long beard and is usually pictured with a dolphin at his side.

Poseidon had a prominent part in numerous ancient myths and legend s. When Zeus fought the Titans a nd the Giants, Poseidon fought at his side and the giant Polybutes by hurling at him a fragment of cliff torn from the island of Cos, which became the islet of Nisyros. After the victory the heritage was divided into three parts, Zeus took the vast heavens, Hades took the murky u nderworld.
Also , A famous story of Poseidon involves the competition between him and the goddess of war, Athena, for the city of Athens. To win the people of the city over, Poseidon threw a spear at the ground and produced the Spring at the Acropolis. However, Athena won as the result of giving the people of Athens the olive tree. In his anger over the decision, Poseidon flooded the Attic Plain. Eventually, Athena and Poseidon worked together by combining their powers.