Ken and Jenny, a doctor and a reporter (Shin'ichi (Sonny) Chiba and Peggy Neal), stumble across the undersea lair of a megalomanic and his army of surgically-modified amphibious cyborgs with which he plans to conquer the world. This juvenile offering from Toei Studios features a mostly Western cast alongside action-hero Chiba (chop-socky fans will be disappointed at the dearth of athletic fights) with a near amateur performance by Neal (to be fair, she has little to work with and spends most of her screen time trying to look horrified). The film contains some reasonably well done underwater miniature work but the centerpiece, the scaly cyborgs are laughable when seen clearly, especially when their costumes are torn. The gilled minions are controlled by the chortling villain through a control box with apparently three settings (off, work, and fight) and are ostensibly brainless (or so we are told) yet seem to know how to effectively use guns. There is an entertaining (if not very convincing) transition scene in which nefarious Doctor Heim (Mike Daneen) creates a cyborg (courtesy of a lot of squishy stop-motion shots intercut with numerous close-ups of Jenny looking increasingly horrified). A later transformation scene involving the heroes leaves the two leads running around with what appears to be pieces of latex stuck to their chins (much to Jenny's horror). There a couple of action sequences involving the undersea-base's defenses vs. An attacking submarine (apparently armed with the X4, a weapon that could "blow up the whole ocean") leading to a finale that includes all of the expected climactic tropes. The film suffers from some editing problems (the scenes in which the heroes are to be transformed seem to be out of sequence or partially deleted) and the overall production including the sound, music, and cinematography, is substandard even for a low-budget Japanese techno-adventure targeting a young audience. I have a fondness for (and a high tolerance of) Japanese science fiction films but 'Terror Beneath the Sea' is pretty awful, even when compared to Toho's dreadful 'Latitude Zero' (1970) or Peggy Neal's other tokusatsu outing, the extremely goofy but entertaining 'The X from Outer Space' (1967).
