This actually scared the hell out of me when I saw it in the neighborhood theater at a Saturday afternoon monster matinee in the sixties. Of course, I was a little kid then.
Now it seems pretty campy. These reptilian/humanoid monsters from the sea -- created by an underwater radioactive waste leak, of course -- rip into various bikini clad girls with their claws. There's a rock band that plays on a pavilion on the beach (the song is called "The Zombie Stomp"), bikers, shirtless guys fighting in the sand, a scientist with a maid named Eulabelle (no kidding) who I kept thinking would start yelling, "I don't know nothin' 'bout birthin' no babies!"...and the "scales" on the monsters pretty much make it look like the costumes are hanging in shreds. Nonstop uninentional laughs.
But at the time, it was pretty daring. It was one of the earliest movies to be gory; it was black and white, and in one scene showed a guy's corpse with his face half torn off. The pace of it is pretty effective, and it has some eerie night photography, and some trippy electronic music. But then you see those "monsters" and you've just gotta laugh. Still a sentimental favorite for me, though.
Like "The Mole People," it was made into a comic book using stills from the film with word balloons added. I sure wish my mom hadn't thrown those out!