According to Reference.com, Poseidon is the god of water and the seas in Greek mythology. Poseidon is the son of Cronus and Rhea, and his brothers include Zeus and Hades. Since he is god of all water, Poseidon is closely connected to the craft of navigation.
Poseidon was worshiped as one of the more important Greek gods. He was considered very powerful and was often vengeful and cruel. Some of his more famous offspring include Triton and Pegasus. The popular image of Poseidon is closely connected to his weapon, the trident. Poseidon was very important to the City of Athens but was considered the most important god in coastal cities like Corinth.