Special camera
Most of the interior shots were filmed using a hand-held Arriflex of cinematographer Jost Vacano's design to convey the claustrophobic atmosphere of the boat. It had two gyroscopes to provide stability, a different and smaller scale solution than the Steadicam, so that it could be carried throughout the interior of the mock-up.[2] Vacano wore full-body padding to minimise injury as he ran and the mock-up was rocked and shaken. The gyroscopes used to stabilize his rig were very noisy, and most of the film had to be dubbed as the location sound was unusable.
Throughout the filming, the actors were forbidden to go out in sunlight, to create the pallor of men who seldom saw the sun during their missions. The actors went through intensive training to learn how to move quickly through the narrow confines of the vessel.