Undersea Super Train: Marine Express

Undersea Super Train: Marine Express is an anime television film created for the Nippon Television Network's annual 24-hour charity program, Ai wa Chikyū o Suku, which roughly translates to "Love Saves the Earth". The film contained a veritable "Who's Who" of manga creator Osamu Tezuka's notable characters. Each one had an important role, and many of them had individual, intertwining stories which would overlap with the ones of others. To coincide with the central theme of the charity program, the film emphasized on the dangers of environmental destruction, and that such disasters can be overcome by banding together.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.