Although the film was shot in color, producer Alex Gordon stopped in a theater where it was showing and was astounded to see that it was being shown in black and white. He checked with Columbia Pictures, the distributor, and was informed that all release prints of the film were in black and white. Gordon could not get anyone at Columbia to explain to him why the film was released that way. Later, when the film was syndicated to television, the prints that were sent out were in color. Gordon couldn't get Columbia to explain that, either.
The floor of the ocean is on a soundstage. The air bubbles are soap bubbles, and you can sometimes see them go up and then come down.
Columbia Pictures chose to offer this film (in the black and white version) on the lower half with Three Stooges Meet Hercules, thereby guaranteeing plenty of exposure, but at the same time, almost total inattention.