Ebirah Horror Of The Deep was originally meant to be a King Kong film titled Operation Robinson Crusoe. When TOHO presented the idea to Rankin/Bass Productions the idea was rejected, but they still made the movie by replacing King Kong with Godzilla.
Once again, there were limitations on the special effects because of the budget. Samasa Arikawa, a special effects specialist who was monitored by Tsuburaya, directed the special effects team and cited the experience as very frustrating also stating that if Tsuburaya was in charge then TOHO would not have made so many demands and that the company knew that he would make the film cheaply. Despite directing the special effects team, Tsuburaya was still given the credit instead of Arikawa.
Ebirah Horror Of The Deep wouldn't see an American release until two years after the Japanese release and it was only shown on TV instead of getting a theatrical release.
Godzilla vs The Sea Monster would be the last movie that audiences would see the twin fairies and the adult form of Mothra until the 1992 film, Godzilla vs Mothra: The Battle For Earth.
When Ryota goes in search for his missing brother, Yata, after disappearing at sea, he steals a yacht with a crew of his two friends and a bank robber believing his brother is still alive. They crash on an unknown island that is run by an evil organization called the Red Bamboo. The organization has been kidnapping natives from the neighboring island, Infant Island, to make heavy water. They are also forced to make a strange yellow liquid that keeps the the giant shrimp monster, Ebirah, away from passing by ships. Whenever a native tries to escape Ebirah attacks and drowns them. One island native girl gets away from the guards and joins Ryota and the group to stop the Red Bamboo. They discover that Godzilla is sleeping on the island and they decide to wake him up with electricity. Godzilla wakes up and he goes to fight Ebirah while the gang infiltrate Red Bamboo's base to rescue the natives while waiting for Mothra to come rescue them.
I don't have much to say about this movie in general. The movie is only alright. It is enjoyable for kids, but it's telling that these movies started going downhill in this one. Godzilla's characteristics drastically changed because the movie was meant to be for Kong. For instance, electricity usually hurts Godzilla, but in this one it gives him more power. There is even a scene where he takes an interest in the native girl and that is another characteristic that belongs to Kong. The fight scenes are comedic at best. The first fight starts off with a couple rounds of playing volleyball and the last fight ends with Godzilla tearing off both of Ebirah's claws and threatening it with Ebirah's own claw like a pair of clippers.
This one is an easy skip. It doesn't do anything new, but it's fun for kids to watch.