Ah, Poseidon. According to mythology, he was the Greek god of the sea who also happened to be associated with earthquakes. Here are some. Area of Rule and Symbols: Picture Poseidon in the sea with his trident. Poseidon: lord and god of sea and rivers. Poseidon became the god of seas and rivers. Poseidon's Symbols Trident One of Poseidon's symbols was the trident. With his trident he could make water appear anywhere. The trident is.