Annapolis graduate, football star, track athlete, wrestling champion, and all-around great guy "Crash" Corrigan (Ray Corrigan) must travel in a rocket-powered submarine to the lost city of Atlantis to stop an invasion of the surface world by the tyrant Unga Khan (Monte Blue)! Assisting him are the inventor Professor Norton (C. Montague Shaw) and his son Billy (Lee Van Atta), reporter Diana Compton (Lois Wilde), and a silly sailor named Briny Deep (Smiley Burnette). The serial is noteworthy for its imaginative array of futuristic technology, the complete absence of women in Atlantis, and the fact that most of the cliffhanger resolutions are "cheats" that do not match the events shown in the preceding chapter. Professor Norton's submarine is pretty amazing too, able to withstand a pressure of 3000 psi! Modern steel submarines can only withstand 580 psi, and even titanium submarines are limited to 1500 psi. (1936 - Republic Pictures)
Trivia: UNDERSEA KINGDOM is stuntman Tom Steele's first film. Monte Blue, who plays the villain Unga Khan, would go on to receive a star on the Hollywood Walk of Fame.
The character of "Crash" Corrigan was created by Republic Pictures as an answer to Universal's Flash Gordon. Since Universal spent $350,000 on its first Flash Gordon serial while Republic spent less than $100,000 to produce UNDERSEA KINGDOM, it is fair to say that "Crash" was a sort of low-budget Flash. The lead actor Ray Corrigan--handsome, muscular and agile--was certainly believable as an action hero, but he would never reach the legendary status of real world Olympic athlete Buster Crabbe. UNDERSEA KINGDOM was a rather crude production for Republic Pictures, being only the second serial in what would become a long list of productions comprising many genres.