Produced as a short experimental trial series of only 3 episodes and filmed in black and white. Inspired in part by the novel "Deep Range" by Arthur C. Clarke, the tale of an undersea boy (Dolphin Prince) with a pet dolphin, who swam in a wetsuit with a built-in jetpack and stunned his enemies with an aqua-boomerang. The episodes featured his mermaid friend Neptuna and Dr. Mariner, with stories entitled "Secret Of The Red Vortex", "Call Of The Sea" and "Attack Of The Sea-Star People."

[Source: Wikipedia and The Anime Encyclopedia]

An expansion of the original Dolphin Ouji series. Character names were altered, (changing 'Dolphin Prince' to 'Marine Kid' and 'Neptuna' to 'Neptina'), characters were added and concepts expanded. In order to distance the new series from the original trial episodes, the series was re-titled Ganbare! Marine Kid.

Marine, whose father, Dr. Mariner, is an oceanographer with the Ocean Patrol, has been genetically altered to have superior underwater swimming abilities and chews Oxygum to supply himself with air underwater. Along with his companion, Whitey the white dolphin (Splasher in the U.S. version), Marine helps his father keep the sea safe.

[Source: Wikipedia and The Anime Encyclopedia]

Yet another expansion of the Marine Boy series. This time 65 episodes were added to the 1966 series and all 78 episodes were sold to the US. The broadcast history of the show in Japan was slightly more complicated, with only the first 36 episodes of the 78 shown at first but later on all 78 were shown, out of which 65 are contained in this entry and 13 in the Ganbare! Marine Kid series.

Marine is now equipped with an underwater boomerang, a hydrojet, and the mermaid Neptuna/Neptina has become his girlfriend. Some previous episodes from Ganbare! Marine Kid had their footage recycled in part for this series.

[Source: The Anime Encyclopedia]