The Secrets of Quetzo
S1:E2
1999
IMDb
Lopaka, a young boy, is taught by his closest friend, a dolphin called Flipper, how to survive underwater so that they can both explore the secrets of Quezo, a sunken city. A giant octopus called Dexter is the evil ruler of the city. Lopaka and Flipper experience many adventures as they try to avoid running into one of Dexter's strongmen.