The top half of one of the seminal 50's Saturday matinee double features (co-feature: Creature with the Atom Brain), Sam Katzman's sci-fi monsterfest petrified a pre-Jaws generation of kids into avoiding the ocean altogether. Atomic subs, on-location San Francisco photography and giant tentacles courtesy of Ray Harryhausen make this one a memorable part of any baby-boomer's childhood.