Sadly, I'm one of those johnnys-come-lately that don't have much use for the deep classics, and I don't pay attention to Marine Boy or your general AstroBoyKimbaAmazingThree Tezuka continuum. I'd point you at Robert Fenelon, Jeff Thompson, or one of the other silverbacks, except I don't know of any of them who maintain a regular weblog or journal. Oh, except for Dave Merrill. He'll be the guy blog/livejournal go-to guy on goofy old cr- childhood memories.
To be honest, the only Marine Boy I've even seen was a ten-second-clip from one of Merrill & Co's Bad American Dubbing clipshows. It struck me as the aquatic love-child of Astro Boy and Johnny Quest, neither of which really engaged my emotions or interest on their own merits.
I think at this point I'd find Astro Boy unwatchable (I saw a documentary on some cable access channel about the show, and was pretty horrified I even watched it as a kid, let alone semi-liked it), but Jonny Quest -- at least the vintage 1960s episodes -- still seem like classics to me.
I've never seen Marine Boy, but it reminds me of a couple of other urAnime shows I used to *love*: "The Seven Cities of Gold" and "Spartacus." Ever seen either of these? I think they were Franco-Japanese, actually, but I remember them as being incredibly high-minded compared to the other stuff Nickelodeon was showing at the time.
Now that I think about it, back before Nickelodeon had the budget to do flashy, American-style stuff on its own, there was some great low-budget international programming on that channel. Turkey TV, some British show about modern pagans, the aforementioned cartoons. Hmm.
Just mindless ruminating-- don't mind me. ;)