Poseidon was the Greek god of the sea and son of Cronus and Rhea. He had many children including Theseus and Triton. Before becoming the god of the sea, Poseidon was known for causing earthquakes. In a battle with Athena over which god would name the city, Poseidon struck the ground with his trident to bring forth a saltwater spring while Athena planted an olive tree. The city chose Athena's gift of the olive tree and was named Athens.