The Tunnel Under the World (original Italian title Il tunnel sotto il mondo) is a 1969 low-budget Italian science-fiction film directed and edited by Luigi Cozzi inspired by Frederik Pohl's novella of the same name. The screenplay was written by Tito Monego and Alfredo Castelli, best known as the creator of the comic book series Martin Mystère.

It was the directorial debut of a 21-year-old Luigi Cozzi. It began as a film school project and eventually wound up becoming a full-length feature film. Cozzi's work on this film brought him to the attention of famed horror film director Dario Argento and jump-started his career.