Das Boot (German pronunciation: [das ˈboːt], The Boat) is a 1981 West German war film written and directed by Wolfgang Petersen, produced by Günter Rohrbach, and starring Jürgen Prochnow, Herbert Grönemeyer and Klaus Wennemann. An adaptation of Lothar-Günther Buchheim's 1973 semi-autobiographical novel of the same name, the film is set during World War II and follows the German submarine U-96 and her crew, as they set out on a hazardous patrol in the Battle of the Atlantic. It depicts both the excitement of battle and the tedium of the fruitless hunt, and shows the men serving aboard U-boats as ordinary individuals with a desire to do their best for their comrades and their country.

Development began in 1979. Several American directors were considered three years earlier, before the film was shelved. During production, Heinrich Lehmann-Willenbrock, the captain of the real U-96 during Buchheim's 1941 patrol and one of Germany's top U-boat "tonnage aces" during the war, and Hans-Joachim Krug, former first officer on U-219, served as consultants. One of Petersen's goals was to guide the audience through "a journey to the edge of the mind" (the film's German tagline Eine Reise ans Ende des Verstandes), showing "what war is all about".

Produced on a DM32 million budget (about $18.5 million, equivalent to €34 million 2021), the high production cost ranks it among the most expensive films in German cinema, but it was a commercial success, grossing nearly $85 million worldwide (equivalent to $220 million in 2020). The film has been exhibited both as a theatrical release (1981) and a TV miniseries (1985). Several different home video versions, as well as a director's cut (1997) supervised by Petersen, have also been released. Columbia Pictures issued both German-language and English-dubbed versions in the United States theatrically through their Triumph Classics label, earning $11 million.

Das Boot received positive reviews, and was nominated for six Academy Awards, including for Best Director and Best Adapted Screenplay for Petersen himself. He was also nominated for a BAFTA Award and DGA Award, and the film won the German Film Award for Best Film. It was the German film with the most Oscar nominations until the release of All Quiet on the Western Front in 2022.