There are times when Godzilla vs the Sea Monster looks to be one of the more compelling and entertaining 'Zilla' movies from the 60's, this despite the fact that the big green guy doesn't show up until 55 minutes(!) into the proceedings. I think what I responded to most positively were two things, and one of these could have been something of a negative but it isn't: first is that it isn't about monsters fighting over a city, and it doesn't involve those aliens or other beings that popped up in the few entries before this one (i.e. Monster Zero), and would show up later again in things like Mecha-Godzilla.
But the other thing, and this may be an aspect viewers won't fully appreciate amid the "B-movie" adventureness of it, is that Godzilla vs the Sea Monster is the first one in the series since, well, could it be the first one(?) that deals with the issue of nuclear energy. The enemies of the film are scientists from some rogue organization - are they affiliated with the government, or more of a Dr. Evil rogue thing, I'm still not sure, the story is only clear enough to get the main beats across that they're using an island to test out their ready-made disastrous weapons - and they make for good foils for our heroes, who make up stowaways and a thief and one guy on the look out for his brother, who is actually on Infant Island.
Does it necessarily mean that director Jun Fukada and writer Senichi Sekizawa are out to make some profound statement about nuclear weapons and such? Maybe not. But I liked that finally we get the return of actual human beings - and sure, one of them has an eye-patch so that, you know, we know he's EVIL - and though they may be easily swayed away when, for example, trying to shine a spotlight at night on our main characters sneaking up to the nuclear weapon lab and they don't see anything despite the fairly bright lights Toho gives to even their night sets, they make for decent villains. The best? Also maybe not. But it is more about their story, how they're using and abusing the natives on the island as slaves, and that they don't know a literal sleeping giant is in their midst under some rocks.
I forget how exactly Godzilla wound up there after the last entry, but no matter: using lighting (what is he, Frankenstein's monster? Actually, this was meant to be a Toho-produced Frankenstein movie, or a King Kong one, either makes sense), Godzilla is resurrected, and fights Ebirah, a giant crab monster. In a way the crab monster isn't even the real threat of the movie, despite that it attacks some people on a boat and fights Godzilla a couple of times. It's more about Godzilla being awoken to make trouble for the nuclear-testing villains, and they become his main targets. There's also a sub plot, kinda, sorta, where the natives on Infant Island keep doing their wondrous chants to Mothra, and it's only in the last ten minutes (barely) that she wakes up to join the fight... against Godzilla this time (?)
I didn't like how they introduced Mothra here and spent so much time on the natives doing their prayer rituals. It was a lot of fun in the past, but here it seemed to be here more-so to take up some screen time. Of course it's always fun to see them at work, but by the time Mothra actually gets into action it's too littletoo late sort of thing. And while Godzilla does get some fun screen time when he shows up, that also comes a little late into the movie which otherwise features this 'Sea Monster' of the title that is little more than a very slightly upgraded version of what Roger Corman cooked up in the 1957 quickie ATTACK OF THE CRAB MONSTERS. It's enjoyable to look at Ebirah. For a minute. And then hesheit wears out its welcome.
But there are things to recommend this movie for, even as it's not the strongest of the 60's movies. I liked the actors playing the stowaways on the boat with the thief who end up becoming the heroes of their own story, they had believable deliveries and made the characters interesting enough (far as a Toho Godzilla movie of the period allows), and I especially loved the music that plays during some of the fights - in particular, during one of those "oh, they're doing THIS again?" moments when planes come around to fire at Godzilla, surf-Rockabilly grooves come up and it makes it... well, is good the word I'm looking for? Actually, yes, it's better than good, it makes for some iconic moments as far as a movie that is squarely in its time in 1966 and the surf music makes it unique.
If only the rest of the movie was that way. But problems and all, Fukuda made a mostly entertaining entry, with some changes (on an island, so the lack of usual stakes made it something else as an adventure-action spectacle), just with some issues that were hard to overlook.
Review by MisterWhiplash from the Internet Movie Database.