Tidying my flat I found my copy of The Anime Encyclopedia, and yes it does have an entry on that Tatsunoko Pro title I’ve been whittling on about these last two weeks.
Apparently it had US dub from Harmony Gold under the name Underwater Encounter, but that doesn’t turn much up either. It was filmed on 35mm and took 2 years to animate. Beyond that there wasn’t much more that I gleaned from sites I quoted before. It’s odd that something that Tatsunoko took so much effort to make has near disappeared from discussion, I wonder if it had had a proper theatrical release it wouldn’t be so obscure.
Wow, I’m very surprised to see your posts on this title! I’ve been trying to track this one down for at least ten years, and I’ve only gotten about as far as you have. I remember seeing this program televised here in the Los Angeles area in 1986, and always wanted to find out more about it… It was the english dubbed Harmony Gold version, and was broadcast on KCOP, if I recall correctly. I can distinctly remember that the main character’s name was Ricky, and that there was another supporting character named Ben. Please do update if you find out anything else about this production.