Pokemon Movie 09: Pokemon Ranger to Umi no Ouji Manaphy

Ash, May, Max, and Brock meet the traveling Marina Group and learn the legend of the Sea Temple, a hidden structure built by the Water People. Their path crosses Pokémon Ranger Jack Walker, who is secretly protecting an egg containing Manaphy, the mythical Pokémon known as the Prince of the Sea.

Manaphy must be returned to the temple, but the pirate Phantom is searching for both the Pokémon and the Sea Crown, a treasure whose power he intends to exploit. May forms an unusually close bond with the newly hatched Manaphy, making the journey more personal as Ash and the others race across the ocean to keep the temple's secret out of Phantom's hands.