The captain leads the crew and a businesswoman to set sail on a distant voyage, exploring the secret realm crystal left behind by the ancient marine civilization. The fleet breaks through volcanic islands and the Lotus Sea secret realm, confronting Black Sail pirates, needlefish tides, and various strange beasts in the sea. Having gone through numerous perils, everyone collects three crystals: crimson, pure white, and deep blue, but the adventure is not over yet. The crystals resonate faintly, and deep in the ocean still hides the last piece of crystal and the ultimate secret of the marine civilization.