When the "dark tide" that occurs once in a thousand years is about to swallow the world, the elemental crystal and the heart of the ocean become the last hope to protect civilization. Luffy and his friends piloted the Golden Merry, starting from the trap of the Deep Sea Altar, crossing the biting cold wind of the Arctic Icefield, passing through the deadly water pressure of the Death Trench, and facing the Blackwater Organization's pursuit and the ferocious interception of the Dark Pressure Beast.
On the way, the mysterious young man Ling Yun appears with ancient crystals, the giant whale of the deep sea turns into a guide, and the betrayal of the guardian of the fog and the secrets of the ancient civilization are revealed layer by layer. From the ice tower activating the guardian core, to the eye of darkness breaking the barrier, to the deep sea castle facing the source of darkness, the partners used sword energy, flames, domineering power and wisdom to break through the situation. In the life and death tests, they used bonds to weave the strongest line of defense against the darkness.
This is not only an adventure to find the power of the seal, but also a passionate hymn about courage, trust and protection - when the tentacles of darkness wrap around the world, only partners who fight side by side can bring light back to the sea.
