Lattitude Zero (1969)
Goofy. Even when they were making this movie, all the involved parties had to have known it was goofy. The submarines are cool, the women hot and the monsters...I like to think of them as a charming homage to Sid & Marty Kroft.
It moves at a good clip, but there are a smattering of dry spots (unless it's just me). There's two versions English and Japanese; the Japanese actors did the dialogue phonetically so there's no crappy English dub to endure. The English version is also several minutes shorter than the Japanese version, perhaps to the movie's benefit.
A goofy good time on a Friday night or Saturday afternoon/night.