This is a great kaiju movie from Toho Studios. Right off the beginning of this film, we see an already intriguing scene when a scientist gets kidnapped by a creature from under the sea. The suspense builds when the creatures reveal themselves to be habitants of the Undersea Kingdom of Mu, and that they have come to Earth to reclaim its land (of course the Earth people do not accept that, so it's the super-submarine Atragon to the rescue). The scenes where it show the origin and the places of the Mu Kingdom are very entertaining. We actually get to see what the Mu Kingdom looks like. The scene where the Mu people sing and dance and worship is a real charmer. For this movie, the special effects by Eiji Tsuburaya are spectacular and the screenplay by Shinichi Sekizawa is exciting, spellbinding, and full of suspense and drama. The plot is solid and perfect and Ishiro Honda's directing is superb. The music by Akira Ifukube is excellent and fantastic. The main title music is full of melody and harmony and is probably my favorite Akira Ifukube music score. And, virtually everybody is in this movie: Tadao Takashima, Yoko Fujiyama, Yu Fujiki, Ken Uehara, Jun Tazaki, Kenji Sahara, Hiroshi Koizumi, Yoshifumi Tajima, Akihiko Hirata, Eisei Amamoto, and Susumu Fujita.
The scenes where the Earth humans and the Mu people battle each other is inspiring. Manda, the giant sea serpent, is an awesome-looking monster. He is the protector of the Mu Kingdom. From the sounds of the worships, Manda seemed to be a powerful creature. However, he is actually pretty weak since he hardly put up a descent battle with Atragon, and he appeared only briefly throughout the entire movie. That was a disappointment - more scenes of Manda would have made this an even better feature. But overall, this film is a great one from Toho.
Grade B+