There are some high-lights here that merit special mention...in no particular order. 1. The professor's hair-do 2. A shower scene of somewhat less than erotic 50's style 3. poison pills deposited in the diving equipment 4. foreign agent Wanda...who she works for we'll never know 5. row-boats that can remain in place on the open sea, with no anchor necessary. Even for 1956, this is an amazing effort. Maybe it was more of a home-movie than a real, studio job. In any case, the morals are presented very clearly and that's what makes it worth my 9 rating. So...beware of mad scientists, spies from un-named evil countries, and monsters in general. But, kids, it's okay to smoke!! P.S. This film seems to have been made before "special effects". There are effects...just not so special.