The sea god in Greek mythology known for his trident is Poseidon. He is one of the Twelve Olympian gods and rules over the seas, earthquakes, and horses. Poseidon is often depicted with his iconic trident, representing his power to control waters and storms. Known for his volatile nature, he was both revered and feared by sailors and land-dwellers alike. His dominion over the sea reflects the significance of water in ancient Greek life, emphasizing both its nurturing and destructive aspects in mythology.