You probably remember the TV show "Voyage to the Bottom of the Sea" which ran from 1964-1968. But before that there was a movie in 1961.
First of all, look who was in this movie! Trivia - Michael Ansara (who later played a Klingon on Star Trek) was married to Barbara Eden while this movie was made.
Walter Pidgon is Admiral Nelson, the inventor of the fabulous nuclear submarine "Seaview". The two distinguishing features of the Seaview are the giant windows in the front and the 1959 Cadillac fins on the back. In the movie, the sub as part of the US Navy but in the TV show, it was part of some marine study institute. The Seaview is on her maiden cruise carrying a few dignitaries, Dr. Susan Hiller (Joan Fontaine) and Congressman Llewellyn Parker (Howard McNear, mostly known as Floyd the barber from Mayberry). Dr. Hiller is there as part of a psychological study of the crewmen and Parker is with a congressional budget committee who always opposed the building of the Seaview and wants to see if the government got it's moneys worth. He carries a notebook and a sharp pencil.
After a few practice dives at under the Arctic ice, the Seaview gets bombarded underwater by sinking chunks of ice. Since ice usually floats this was a surprise. The Seaview surfaces and finds that the sky is on fire. Admiral Nelson learns from Naval command that a errant meteor has set the Van Allen Radiation Belt on fire! The Van Allen Belt had only just been discovered in 1958 so I guess it sounded plausible. The air temperature was already 130 degrees. Before they leave, they see a guy laying on a hunk of ice and rescue him and his dog. What he was doing there is never explained. This is Miguel Alvarez (Michael Ansara).
The crew hightails it to New York to meet with a UN expert panel of scientists. On the way, Nelson and Comm. Lucius Emery (Peter Lorre) concoct a scheme to launch a nuclear missile at the burning belt to blow out the fire. Emery's role on the Seaview is unclear. He seems to spend much of his time studying the sharks that Seaview have in a giant tank on board. The missile has to be launched at some precise location in the Pacific Ocean at a precise time in order to work. By the time Nelson arrives at the UN, some crazy scientist on the panel had already convinced them that the fire would burn it self out at 173 degrees. By then of course everybody would be dead and the planet a cinder (which nobody mentions). Nelson, insisting that only his plan would work, storms out of the UN and takes off in the Seaview.
The TV pilot had a similar plot, only it was a earthquake that was going to occur in the Arctic which would send devastating tidal waves into the Atlantic and Pacific. Nelson blew up a nuke to stop the earthquake.
After many adventures, the Seaview gets to the launch point and saves the day.
Some charactor notes:
Admiral Nelson is pretty much a megalomaniac who is convinced he is right and doesn't care what happens to anyone as long as he gets his way. This character was toned way down for the TV show.
Captain Lee Crane (Robert Sterling) is played pretty straight as the boat's commanding officer who gets increasing worried about his superior officer's seeming increasing insanity. In the TV show, Crane is the solo real Naval officer on board.
In a surprising move for 1961, the Seaview has a woman officer, Lt Cathy Conners. Of course, she's played by Barbara Eden, and is engaged to Lee Crane. She spends a lot of time hanging all over the captain and screaming.
Already mentioned is Comm. Lucius Emery (Peter Lorre). He mostly seems like a absent-minded professor.
Joan Fontaine as Dr. Heller is interesting. It's not clear how long she was supposed to be aboard the Seaview but she is wearing a different outfit pretty much every time we see her. BTW, she and Barbara Eden wear high heels. On a submarine. Her function seems to be to convince Crane that Nelson is crazy and will kill them all. Eventually, convinced of this herself, she goes into the reactor room and somehow sabotages it, getting a lethal does of radiation (shown by the badges everyone wears) in the process. But we don't have to watch her slowly die as she falls into Emery's shark tank and gets eaten alive. Really.
Miguel Alvarez (Michael Ansara), the mystery man from the Arctic, turns out to be some kind of religious zealot who spends his time trying to convince the crew that we are all helpless against God and if God wants to burn the world down, there's nothing we can do about it. The movie comes down to a religious discussion between Alvares (who has a bomb he found conveniently laying around) and Nelson. While this is going on, Crane, goes outside the sub and somehow launches the missile by hand.
After the missile launches, the Seaview surfaces and everybody goes out on the deck so they can watch the nuke explode right over their heads.
OK, here's a special treat, Frankie Avalon singing the love theme from "Voyage to the Bottom of the Sea". I strongly recommend you don't listen to more than 15 seconds of this.