Superman: The Underground World

Lois Lane is taken prisoner by a race of bird-men living in caverns beneath the earth after a mining expedition discovers their hidden world, and Superman has to burrow down to rescue her before she is thrown to a lake of lava. The last of the seventeen Fleischer/Famous Studios Superman shorts and one of the strangest — directed by Seymour Kneitel with Bud Collyer and Joan Alexander voicing Superman and Lois. The film entered the public domain through non-renewal.