City Beneath the Sea is a 1971 adventure science fiction television movie and television pilot for a proposed series by Irwin Allen featuring Stuart Whitman and Robert Colbert. It began as a conceptual 10-minute demonstration reel as a means to sell the plot and concept to television studios. The concept was not bought initially, and a few years later Allen produced it as a two-hour television movie for NBC. The two-hour movie failed to gain the response necessary for a series. In the UK it was shown theatrically in 1972 as One Hour To Doomsday.

It was released in DVD form as part of the Warner Archive Collection.