Dora and Boots were picking up trash on the beach when a talking clam shell told them about the Mermaid Kingdom.

The clam shell explained how a mean octopus had dumped trash in the Mermaid Kingdom, causing it to vanish.

Mariana, a young mermaid, told Dora and Boots about a magic crown that could save their kingdom.

With the magic crown found, Dora and Boots were ready to set off to the Mermaid Kingdom.

They crossed the Sea Shell Bridge by correctly identifying the numbered shells despite the octopus' attempts to thwart them.

On Pirate Island, they encountered Swiper who tried to swipe the crown but ultimately returned it.

They stopped the whale in time and got Swiper to swipe the garbage off the whale, a first for him.

With the whale saved, Dora and Boots continued their journey to the Mermaid Kingdom.

Upon arrival, they saw the damage caused by the octopus and the sad state of the mermaids and mermen.

Dora and Boots vowed to help Mariana and her kingdom by using the magic crown to clean up all the garbage.