Iron Lung
A rated-R sci-fi horror film in which a convict pilots a windowless submarine through a moon's ocean of blood in a post-apocalyptic future. The film is rated R for language, bloody images, and gore, and carries sustained psychological and body-horror intensity throughout its full 125-minute runtime.
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Establishes the blood ocean setting; blood is visible seeping through hull cracks from early on, setting the film's baseline of pervasive bloody imagery.
A disembodied radio voice describes asphyxiation as among the more pleasant ways to die at the ocean's depths; the mission is referred to as an execution rather than a genuine expedition.
Simon discovers boils forming on his own skin after blood contact; a separate character is confirmed to have died of radiation poisoning caused by Simon's accidental irradiation.