Pokémon Ranger and the Temple of the Sea(2006)

Pocket Monsters Advanced Generation: Pokemon Ranger to Umi no Ouji Manaphy

It all started with a legend passed down from the People of the Water...

Somewhere in this world, there is a temple created by the People of the Water. The Sea Temple contains a hidden treasure, the Sea Crown, but no one has ever seen it because the temple is protected by a secret mechanism. So it drifts through the vast ocean undetected, waiting... waiting...

Ash and Pikachu learn about the legend and meet Jackie, a Pokémon Ranger on a mission to protect a Manaphy egg and find the temple. The Phantom, a nefarious pirate, plans to obtain the Sea Crown and take over the world--but first he needs the Manaphy egg. What is the Sea Crown? How does Manaphy's mysterious power connect it to the Sea Temple? Can Ash help Jackie complete his mission?

(Source: VIZ Media)