Sally Jane Black’s review published on Letterboxd:
Starring a very silly chicken, this film is a B-movie that flubs its central draw (other than the chicken). It's about a city under the sea, but the way they depict the undersea segments, while kinda clever, leave a lot to be desired visually. While I appreciate the practical approach over today's digital hideous, I have to admit there are times practical didn't cut it. It looks like jarringly ugly stock footage, and I would assume that's what it was if not for the fish-people in it.
Other major flaws include an overlong, clunky fight underwater and Tab Hunter's dubbing/voice (not sure which it was). The strengths include Vincent Price (of course) and some fine sets. The city itself is mostly just some nice looking caverns, but they work well enough. The other strength is the script's darkness; several men are left to die at times in ways that are--while off-screen--still unpleasant, and the final death is shown with a nice bit of special effect.
Unfortunately, it's still a bit of an underdeveloped send off for Tourneur.
December count: 50/100.