Scientists working in an underwater laboratory decide to create a race of amphibious humans.
Time and again, Irwin Allen programs show more interest in the sizzle of melodrama over the steak of thoughtful science fiction, but this episode is more straightforward and still tells a good story.
Sure, it's loaded with science mumbo jumbo, but it starts with a half-plausible explanation of life's evolution under the sea and the embryology of terrestrial organisms. Of course, then it goes on to the wackiness of surgically implanted gills that end in microphone caps that are glued on the neck of actors (amazingly spotted as "proof" of "amphibian experiments" on videotape by Nelson). But leaving that aside, the plotting is brisk and deals with one topic at a time. The underwater scenes are good - though almost all episodes seem to feature one shot of divers framed against sunlight on the surface (even when supposedly taking place 100s of fathoms down) and the mushroom-shaped science lab is not one of the better miniatures.
Skip Homeier, one of the 60s TV's poster boys for crazy followers of insane ideas, is his usual memorable self here, spouting dialog proclaiming man's destiny as creatures of the sea. What makes this installment one of the best examples of "Voyage" is its simplicity, a terrible idea that goes more and more wrong, the Sea View countering the unfolding plot step-by-step, and a dramatic conclusion that while scientifically dopey at least brings all the issues to a satisfying finish.