Dora the Explorer: Dora Saves the Mermaids(2007)

"It's Clean-Up the Beach Day, as Dora and Boots are cleaning up garbage when they find a Singing Clam, who tells them the story of Mariana the Mermaid. Mariana lives in the Mermaid Kingdom at the bottom of the ocean."

Overview

In this release Dora and Boots take preschoolers on exciting under water adventures to help save the mermaid’s kingdom, travel to the bottom of the ocean and find a hidden treasure chest on Treasure Island!