The project originally began as a US co-production with American company Presman Incorporated, planned to have an all-American cast with Robert Redford as the U-boat commander, and directors like John Sturges, Don Siegel or Sydney Pollack were considered.

Author Lothar-Günther Buchheim rejected the American screenplay written by Ronald M. Cohen, calling it a 'Japanese-style action extravaganza' because it was too patriotic and action-focused, which led Presman Inc. to withdraw from the project.

Buchheim himself then wrote a 600-page script that would have resulted in a five-hour film before Wolfgang Petersen was brought in to write a new, shorter screenplay.

Set designer Rolf Zehetbauer had already started building several scale models of the submarine before the screenplay, lead actor, or even the director had been finalized.

Director Wolfgang Petersen wanted Jürgen Prochnow for the lead role of the commander for years, but he was initially rejected for being too young; he was eventually cast after it was noted that photos of the real submarine crew showed men who looked much older than their actual age.

Jan Fedder was originally supposed to play a sailor from Cologne, but as a native of Hamburg he refused, and since the character's regional origin had no impact on the story, the role was adjusted to fit his own background.

According to director Wolfgang Petersen's audio commentary on the Director's Cut DVD, actor Otto Sander was genuinely drunk during the filming of his introduction scene as the alcoholic Kapitänleutnant Thomsen.

The entire film was shot without live sound recording because of the noise from the hydraulic motion platform and the poor acoustics of the metal set, meaning all dialogue had to be dubbed afterward.

Actors were forbidden from sunbathing during the summer shoot to prevent tanned skin, and were required to stop shaving ten days before filming the later scenes, mirroring the real Navy practice of not shaving during patrols to save fresh water.

Because the set was too cramped for a Steadicam, cinematographer Jost Vacano used gyroscopic stabilizers for handheld shots, a technique he had already used in 1973 on the film Supermarkt.

For storm scenes, a water cannon could blast one ton of water against the conning tower per wave, and Petersen eventually moved the set onto a hydraulic platform to simulate the boat's pitching and rolling motion.

During a storm scene, actor Jan Fedder's character was actually swept off the bridge by a real wave during filming, resulting in an on-set accident.

A hydraulic lift once collapsed in the studio when a safety strap failed, though no one was injured.

For budget reasons, the climactic harbor air raid finale was filmed in a single take using two modified French aircraft.

Producer Bernd Eichinger won a Porsche 911 in a bet with Wolfgang Petersen after correctly predicting that the film's audience numbers would be higher than Petersen estimated.

Buchheim later criticized the scene where a sailor performs a dance wearing only makeup and bananas around his waist (a reference to Josephine Baker's 1926 Banana Skirt Song), saying such a thing would never have happened on a real German U-boat, though it was loosely inspired by a scene in the novel of a sailor dancing naked.

The eccentric Kapitänleutnant Philipp Thomsen character was based on a real person, Korvettenkapitän Karl Thurmann.

The commander in the novel, referred to only as 'the Old Man,' was based on Heinrich Lehmann-Willenbrock, the real commander of U 96 whenever Buchheim was aboard; he survived the war, died in 1986, and was present once during filming.

The film was nominated for six Academy Awards, including Best Director and Best Cinematography, as well as a Golden Globe and a BAFTA Award, and won numerous German film prizes.

With a budget of 32 million Deutsche Marks (equivalent to about 41.9 million euros in 2024), Das Boot was an extremely expensive production by German standards, even by today's measures.

The film helped launch the Hollywood careers of director Wolfgang Petersen and cinematographer Jost Vacano, and served as a career breakthrough for many of its cast members, most of whom had previously worked mainly in theater.