After a shark attack leads to Cleo and Puffer's eight-legged octopus friend Ollie getting lost in the ocean, a fun-loving manta ray named Crash helps them search the sea to find their lost mate. Along their journey they meet all sorts of fascinating creatures of the deep and learn about each and every one of them during their aquatic adventure..

When Fifi and her best friend Lily the whale get lost during a field trip to visit a sunken treasure ship, they embark on a incredible adventure to return home and reunite a lost sting ray with her parents.

Fin and Fifi are nervous before their first day of school. However, once they arrive and see their excited classmates, the brother and sister fish begin to relax and discover that they enjoy learning about interesting subjects and going on fun undersea adventures.