Many years ago, the Queen of Atlantis (Nicole Kidman) and humans knew each other and fell in love, and together they gave birth to the fruit of love-Arthur Curry (Jason Momoa), who was later called the King of the Sea by the land people. In the process of growing up, Arthur accepted the rigorous training of the underwater mentor Weike (Willem Dafoe), always eager to visit his mother, but as a mixed-blood illegitimate child, this is a luxury. At the same time, Arthur's half-brother Aum (Patrick Wilson) became the king of Atlantis. He was dissatisfied with the poisoning and pollution of the sea by land humans, so he planned to unite other underwater kingdoms to launch a full-scale war on land. In order to stop his ambition, Weike and Aum's fiancee Mera (Amber Heard) took Arthur to the underwater world. Fate pushed Arthur to find the long-lost trident and establish a more enlightened underwater kingdom...