Tiefland ("Lowlands") is a 1954 West German opera drama film directed, produced, co-written, edited by and starring Leni Riefenstahl, and based on the 1903 eponymous opera composed by Eugen d'Albert to a libretto by Rudolph Lothar based on the 1896 Catalan play Terra baixa by Àngel Guimerà. The film co-stars Bernhard Minetti, and is Riefenstahl's last feature film as both director and lead actress.

Riefenstahl started to develop the script in 1934, with the movie being shot between 1940 and 1944. However, it was not completed by the end of World War II and was eventually finalized and released on February 11, 1954. It was once listed as the feature film with the longest production time in history by the Guinness Book of World Records. This record was later surpassed by The Thief and the Cobbler (with 29 years of production from 1964 to 1993), and there exist films with production times that are longer still.

Riefenstahl's movie is the second Tiefland film that is based on the opera, the first one being a silent film in 1922, directed by Adolf E. Licho, with Lil Dagover as the main actress. The earlier American silent movie Marta of the Lowlands (1914) was based on the English translation of a Spanish translation of Guimerà's play.