Pokemon Ranger to Umi no Ouji Manaphy  

Pokemon Ranger and the Temple of the Sea, ポケモンレンジャーと蒼海の王子 マナフィ

The story begins with a legend shared among the Water People, who created a temple in the ocean known as the Sea Temple. This temple holds a hidden treasure called the Sea Crown, which is guarded by a secret mechanism that prevents anyone from discovering it. Despite this, Ash and Pikachu come across the legend and meet Jackie, a Pokémon Ranger on a mission to protect an egg of the Manaphy species and locate the temple. The Phantom, a notorious pirate, seeks to obtain the Sea Crown in order to rule over the world, but first he must acquire the Manaphy egg. What is the Sea Crown? How does it connect with the mysterious power of Manaphy? Can Ash assist Jackie in completing his mission?

Pokemon Advanced Generation: Pokemon Ranger to Umi no Ouji Manaphy was published in English as Pokémon: Pokémon Ranger and the Temple of the Sea by VIZ Media on August 5, 2008.