Fifteen years ago, the Kingdom of Waves and Abyss were wrapped up in a terrible war. In order to win the war, the kingdom used the power of the Gems of Tide to nearly destroy Abyss. Now, with Abyss slowly recovering, its new ruler Ceto has struck back and seeks the Gems of Tide to exact revenge. It's up to Marie, Natasha, Talia and Ruth to fight Abyss as Precure Ocean Splash!