The ancient Greek god of the sea was Poseidon. In mythology, Poseidon was one of the twelve Olympian deities and was known for his temperamental nature and powerful control over oceans, storms, and horses. Often depicted holding a trident, he was not only the god of the sea but also of earthquakes and tidal waves. According to mythology, he was the brother of Zeus and Hades, and all three were significant figures in Greek lore. Poseidon played a crucial role in many myths and was worshipped by sailors and coastal communities seeking his favor for safe travels and bountiful catches.