If you are looking for a beautifully filmed underwater thriller with an amazing creature as its centerpiece, the Roger Corman produced Monster From the Ocean Floor is not it! Turn to Creature From the Black Lagoon (1954) for that distinction. However, this does not mean that Monster is a total red hot mess...but it comes pretty close!
On the positive side, the underwater sequences are nicely filmed which means that director Wyott Ordung was not totally incompetent. Yet I have the feeling that the credit for this actually goes to cinematographer Floyd Crosby who did such a magnificent job with House of Usher (1960).
Now the bad news...audience may have been lured into the theater with the promise of an undersea adventure, but what they really got was a low budget creature feature with a giant irradiated one-eyed amoeba/octopus that makes the creature in Ed Wood's Bride of the Monster look good. Wow! Everything about it simply did not work.
Furthermore, the screenplay was underwhelming and played into 1950's paranoia about atomic radiation that somehow made everything grow to gigantic proportions and cop a mean attitude. Puh-lease! Turn to Them! (1954) to see how this theme is done right.
I don't want to waste any more time reviewing this film. Stick with the others two I've mentioned and leave this one on the bottom of the ocean floor where it rightfully belongs. Download it from Archive.org at your own peril.
Download a copy of the film from Archive.org
For more info check out the film's entry in IMDB.