City Beneath the Sea is a 1971 science fiction film directed by Irwin Allen. The film takes place in the year 2053, where a group of scientists and engineers inhabit Pacifica, an underwater city that was initially built for scientific reasons. The city is located in the Mariana Trench and is home to a community of approximately 300 people.
The U.S. government wants to use Pacifica to store the nation's gold reserves and a new radioactive element that has been discovered. The government assures the inhabitants of Pacifica that the gold will be used to pay for the development of new technology that will benefit everyone.
However, the brother of Pacifica's former commander, who was killed in an earlier mission, plans to steal the gold. He enlists the help of a group of mercenaries and sets out to take control of Pacifica and the gold.
Meanwhile, a massive asteroid is discovered to be heading towards Earth, and Pacifica is directly in its path. The inhabitants of Pacifica must work to prevent the asteroid from destroying the city and, ultimately, the Earth.
The film features a cast including Stuart Whitman as Hank Slattery, the leader of Pacifica; Robert Wagner as Paul Tristram, the former commander's brother; Rosemary Forsyth as Dr. Susan Hill, a scientist in Pacifica; and Richard Basehart as Admiral Matthews, a U.S. government official.
City Beneath the Sea is notable for its special effects, which include underwater photography, miniatures, and matte paintings. The film was released to mixed reviews but has since become a cult classic for fans of science fiction and disaster films.