The Deep Sea King rules the Seafolk and claims the deep ocean as his own territory, planning to seize the surface world next. On land, dehydration keeps him in his most humanoid form — a large, muscular, aquamarine being with dark-toned arms, legs, and back, facial fins, sharp eyes, large fangs, an ornate crown, a fur-trimmed cape, and a heart-shaped marking over each nipple in place of the usual anatomy. When properly hydrated, his true form emerges: significantly larger, with dramatically expanded muscles, larger fins, new fins growing along his forearms and shoulders, and a far more monstrous face.
He is sadistic by nature, drawing genuine enjoyment from causing pain and provoking fights, and views humans as barely more than food — a conviction that fits his broader belief that he sits at the very top of the food chain of every living thing on Earth. His campaign to claim the surface world puts him directly against a coalition of heroes including Mumen Rider, Genos, Puri-Puri Prisoner, and eventually Saitama.
Standard "dehydrated" state: a tall, muscular, pale scaly fish-man with webbed fin-like ears, a shark-toothed mouth, dark eyes, small heart-shaped pectoral markings, and a red crown, draped in a fur-lined dark royal cloak. Exposed to rain or water, he transforms into a larger, more piscine, monstrous "True Form" with bigger teeth and pronounced gills.
Arrogant, sadistic, and deeply elitist, viewing humans as biologically inferior organisms that exist purely to be conquered. Genuinely observant and capable of psychological warfare, mocking his opponents’ sense of justice — but ultimately undone by his own narcissism, dismissing Saitama as a "nobody" right up until the moment of his death.
Sovereign ruler of a massive aquatic clan hidden from human civilization for centuries, holding absolute authority over all Seafolk messengers and warriors.
Arrives in City J after his scouts are defeated, effortlessly beating Stinger and Lightning Max. Withstands Puri-Puri Prisoner’s "Angel Rush" without real damage and counters with his own Consecutive Normal Punches. Outpaced briefly by Speed-o’-Sound Sonic in his dry state, he transforms into his True Form once it starts raining and forces Sonic to retreat. Tracks civilians to a shelter, is engaged by Genos (who briefly blows him out of the building with an incineration cannon), but wins after Genos is distracted protecting a child from an acid-spit attack. Mumen Rider makes a doomed final stand to buy time before Saitama arrives, punches through his torso in a single strike, and kills him — the resulting shockwave clears the storm overhead.
Raw strength enough to punch through reinforced shelter walls and S-Class armor, near-instant regeneration, a hidden secondary eel-mouth for surprise bites, and acidic spit that melts cybernetic alloy. Hydro-Adaptation: his speed and durability spike dramatically when wet, and correspondingly fade if kept dry too long.
vs. Stinger & Lightning Max
Ambushed both heroes right after they'd taken down his messengers. Total victory — both incapacitated in the same fight.
vs. Puri-Puri Prisoner
Withstood the Angel Rush and countered with even more force.
vs. Speed-o'-Sound Sonic
A pure speed duel through the streets of City J — Sonic pulled out once the King fully transformed.
vs. Genos
Tore through a civilian shelter fight using acid spit and tactical strikes to take the cyborg apart.
vs. Saitama
The final confrontation, in the rain. One punch ended the entire Seafolk invasion — and kicked off the public controversy over Saitama's ranking that follows him for the rest of the series.
Major: Ch. 23–27. Minor: Ch. 28 (remains). Mentioned only: Ch. 31, 46, 47, 171, 201.
The Seafolk Clan: his loyal subjects, who worshipped him as a god-king. Saitama: the man who killed him, without the King ever learning his name. Genos: an opponent he genuinely respected for his fighting spirit before dismantling him. Mumen Rider: dismissed as a pathetic show of human futility. Sky King: a rival who moved to claim the surface once the Deep Sea King was gone.
“I am the Deep Sea King. And now I rule here.”
“The sea is the source of all things, sort of like a mother... and I stand atop the pyramid of life!”
His death left the surface "unclaimed," directly prompting Sky King’s subsequent invasion attempt. His "Consecutive Normal Punches" is a direct parody of the same move Saitama used on Beast King.
🇯🇵 Japanese Voice Actors
Koyama, Rikiya
🇯🇵 Japanese
🇺🇸 English Voice Actors
Silverstein, Keith
🇺🇸 English