It Came from Beneath the Sea (1955)

We're told that the US Navy submarine on which leading man Kenneth Tobey operates is "man's greatest weapon of the seas", so naturally in the depths there exists something more destructive: a hungry cephalopod, giant size.
The scientist phase of the story is paired with the romance sub-plot, but the real treasure is the 'It' of the title. It's not until near fifty minutes have passed that we get a first real glimpse of the creature. When it returns later to lay waste to a famous landmark — because the law of giant monsters states that non-famous ones aren't worth bothering about — it steals the show! Or rather, its animator Ray Harryhausen does. To be frank, the non-creature parts of the film are okay, but the many-tentacled terror is the high-point. It's by far the best stop-motion animated octopus that I've personally ever seen.

3 closed beaches out of 5