The polar ice caps have melted due to global warming. The human race has been stuck on one island as the marine life begins to evolve. Kids use a submarine and the help of their robot companions to explore the depths and come upon an ancient secret underwater civilization with treasure. It's a new hope for the human race to live under water but a money hungry real-estate tycoon stands in their way of peace.
Aqua Kids is a South Korean series but aired in Japan first. Since Japan had the first TV airing, the air date will reflect it rather than South Korean's airing (September 13, 2004 - December 14, 2004).