"Umi no Triton" is a 1972 anime series based on the manga by Osamu Tezuka, blending fantasy, adventure, and environmental themes. The narrative centers on Triton, the last surviving member of the sea-dwelling Poseidon clan, who seeks revenge against the Poseidon clan's oppressors, the Triton clan. The Triton clan, led by the tyrannical King Poseidon, wiped out Triton's people, leaving him as the sole heir to their legacy. Triton is raised by a kind fisherman and his daughter, Sara, who teach him human values and compassion. However, his peaceful life is disrupted when the Triton clan discovers his existence, forcing him to confront his destiny.

Triton wields the magical trident, a powerful weapon that grants him control over the seas and marine life. As he embarks on his journey, he encounters allies and adversaries, including the mermaid Ruka, who becomes a loyal companion. Together, they navigate the complexities of the underwater world, facing challenges such as the Triton clan's relentless pursuit and the moral dilemmas of wielding immense power. The series explores themes of vengeance, justice, and the balance between humanity and nature, as Triton grapples with his dual identity as both a protector of the seas and a warrior seeking retribution.

The plot unfolds through episodic adventures, with Triton and his allies confronting various threats posed by the Triton clan and other sea creatures. Key antagonists include King Poseidon and his generals, who embody the destructive tendencies of unchecked power and exploitation of the ocean. As Triton grows stronger and more determined, he begins to question whether his quest for vengeance aligns with his role as a guardian of the seas. The series culminates in a climactic battle that tests Triton's resolve and forces him to reconcile his personal vendetta with his responsibility to protect the marine world.

"Umi no Triton" is notable for its early exploration of environmental themes, presenting the ocean as a fragile ecosystem threatened by greed and conflict. The characters, particularly Triton and Ruka, are developed through their interactions and struggles, highlighting their growth and the moral complexities of their journey. The series remains a significant work in anime history, blending action, fantasy, and thought-provoking themes in a narrative that resonates with audiences.