Rifftrax, please riff "Terror Beneath the Sea"
It's as if a grade Z Japanese studio thought that the combination of "Mighty Jack", "The Horror of Party Beach", "The Green ", and "Creature from the Black Lagoon" all mixed together would make a great idea for a sci-fi flick. Add wooden actors, poor writing, absentee direction, slapdash makeup and "special" effects, along with off the rack creature costumes, and you have the riffalicious gem which is "Terror Beneath the Sea". Mad scientist (mostly angry, but who is still a little whacked) creates a utopia on the sea floor, while engineering his sea creature "cyborgs" from human participants into creatures by apparently microwaving them and replacing their lungs. These overgrown pollywogs, which serve as labor controlled sonicly by a three position rotary switch, kidnap our protagonists while out for a scuba dive, who also happen to be friends with Naval officers in a futuristic sub with headlights and smart torpedoes that make bank turns like "Mighty Jack". All this happening around undersea atomic waste dumps that probably gave Gerry Andersen his idea for creating "Space 1999", though spoiler alert; the explosions didn't knock the ocean out of Earth's orbit.
Christopher Tonstad commented
Oh, and a young Sonny Chiba stars, but kicks relatively little *** in this mess.