In the ocean, there are four magical crystals. The dark corps led by sea monster Limo Ansen tried to get the crystals by all means and dominate the ocean. The deep-sea ranger-led by Xiaoronglong waged fierce battles with them in order to maintain the security of the ocean. In this period, two octopus siblings were involved in the struggles. With the help of Octopus siblings and in reliance on their courage and wisdom, Xiaoronglong and his friends resolved the crises time and time again and eventually defeated the dark forces and maintained the peace of the ocean.