Aqua Kids(2004)

Aqua Kids

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.