It Came from Beneath the Sea (1955)

Plot

A monstrous octopus, mutated by radiation from H-Bomb tests, emerges from the depths of the Mindanao Trench, wreaking havoc along the California coastline. As it terrorizes coastal towns and ships, a dedicated team of scientists and military personnel must join forces to confront this terrifying creature. With the threat escalating, they race against time to devise a plan to stop the relentless beast before it claims more victims. Tension mounts as they confront both the creature and the consequences of humanity's own destructive actions.