Marine Boy made its first appearance in the United States in 1966. It was the color cartoon produced in Japan and held by some to be the grandfather of Anime . . . at least in the US. Warner Bros. has announced they are releasing the original series, no doubt remastered, on DVD.
Sounds pretty cool. You can't go wrong with dolphin-riding aquatic super child hero whose best friend is a mermaid, all teamed together to save the world.