The Greek god of the sea, often depicted with a trident, is Poseidon. He is one of the major Olympian deities and represents not only the sea but also earthquakes and horses. Poseidon is known for his temperamental nature, capable of both providing bountiful seas and inflicting devastating storms. His influence over maritime activities and navigation made him a vital figure in ancient Greek culture, showcasing the gods' power over nature and their role in human affairs.