The Sea God is a 1st Class God in the Divine Realm. He has the ability to control the seas and is worshiped by sea-type spirit beasts and spirit masters.
Poseidon was the original Sea God. He encountered Tang San through the Vast Sea Cosmic Shroud. At that moment, he designated Tang San as his successor. When the Shrek Seven Devils arrived on Sea God Island, Poseidon bestowed Tang San the Seagod Trials. Tang San became the Sea God after completing the Seagod Trials. After becoming the Sea God, Tang San battled with the Angel Goddess, Qian Renxue, ending in her defeat. He helped the other Shrek Devils break through rank 90 before heading to Purple
Xiao Wu can temporary become the Sea Goddess when Tang San uses the power of the Asura God.