Yoinked from wikipedia and the truly awesome 1000misspenthours.com ...
"The Beach Girls and the Monster is a horror film in the beach party style. Unlike most beach party films, it was shot in black & white. For some release prints, the surfing footage was printed in color. The onscreen copyright is 1964, although the film was not released until September 1965.
What we’re looking at here is an early offering from AIP-TV, the same powerhouse of crap that gave us Mars Needs Women and Space Probe Taurus. In light of this fact, we should prepare ourselves for two things: 1). the movie’s going to be more heavily padded than an out-of-shape sumo wrestler; and 2). when it’s not busy boring us, the movie’s going to try to make our brains explode from the effort of trying to keep up with its insanity.
I’ll say this for The Beach Girls and the Monster, though— it comes out swinging. Six young people of indeterminate age (they act like they’re supposed to be teenagers, but certain details of the script make sense only if at least one of them is well into his twenties) are hanging out at the beach. The guys are out riding the waves (oh— did I forget to mention that this is a surfsploitation movie?) while their girlfriends are wriggling semi-rhythmically (one hesitates to call it 'dancing') on the dunes to the strains of some rather tepid generic surf-rock written by the one and only Frank Sinatra Jr. Sure does simplify matters when the characters’ transistor radios are tuned in to the movie’s own incidental music, huh?
Anyway, after the boys return to the land, a girl named Bunny (Gloria Neil) goes running off behind one of the larger dunes for no particularly good reason. Standing conveniently between a crevice in a nearby rock-face and the mouth of a big-ass drainage pipe, Bunny is ideally placed for attack by, say, a gill-man, and when one of those happens along a few moments later, she is defenseless against its leisurely lumbering might. The gill-man strangles Bunny, scratches up her face a bit (everyone knows facial lacerations are fatal in cheap horror movies), and crawls away down the pipe. Her friends are suitably horrified to discover her body shortly thereafter.
The surfing footage used for the scene where Richard runs a film for Mark was shot by one of the most prolific surf filmmakers of the 1960s, Dale Davis, who produced Walk on the Wet Side, Strictly Hot, and the landmark The Golden Breed. According to the trailer for the film, the dancing girls seen in the movie are The Watusi Dancing Girls from Hollywood's Whisky a Go Go club on Sunset Boulevard. Most of the interior shots - specifically all those of the Lindsay home - were shot at the actual home of director and star Jon Hall.
All the sculptures and the Kingsley the Lion puppet used in the film, were created by the actor who played Mark - Walker Edmiston, the host of The Walker Edmiston Show, a children's television program in Los Angeles that featured featured puppets of his own creation including Kingsley the Lion.
Brian Chidester & Dominic Priore state in their book, Pop Surf Culture, that 'the soundtrack of The Beach Girls and the Monster has got to rank up there among the best … no fewer than 13 different sections of full-bore, deep-reverb tank surf instrumentals throb the soundtrack.' The score was arranged and conducted by Chuck Sagle, and a few of the musicians assembled for the soundtrack were members of the surf band The Hustlers (who are known for their songs Kopout, Inertia and Wailin’ Out) from Riverside, California. According to the film's credits, the theme song titled 'Dance Baby Dance' was written by Frank Sinatra, Jr. and Joan Janis, and produced by Edward Janis."