Undersea Kingdom (1936) is a Republic Pictures film serial in 12 chapters released in response to Universal's Flash Gordon.

Following a suspicious earthquake, and detecting a series of signals, Professor Norton leads an expedition, including Lt Crash Corrigan and Reporter Diana Compton, in his Rocket Submarine to the suspected location of Atlantis. Finding the lost continent they become embroiled in an Atlantean civil war between Sharad (with his White Robes) and the usurper Unga Khan (with his Black Robes) who wishes to conquer Atlantis and then destroy the upper world with earthquakes generated by his Disintegrator. Thus he will rule the world unless he can be stopped in time.

The star of the serial is Ray "Crash" Corrigan, using that screen name for the first time. The name was created to sound similar to "Flash Gordon", in one of many similarities. Formerly a stunt man — he was the person swinging on vines in Tarzan the Ape Man — Corrigan went on to use this screenname for the rest of his career in serials and B-Westerns.

Cast:
Ray "Crash" Corrigan as Crash Corrigan
Lois Wilde as Diana Compton
Monte Blue as Unga Khan
William Farnum as Sharad
Lon Chaney, Jr. as Captain Hakur, a supporting role

text from wikipedia