
Set in a bleak, post‑apocalyptic world after the Quiet Rapture, a condemned prisoner pilots the cramped submarine Iron Lung across a crimson, blood‑colored ocean that covers a desolate moon. Driven by a desperate mission, he dives into the hostile depths to locate the vanished stars and lost planets, confronting isolation and danger at every turn.
Does Iron Lung have end credit scenes?
Yes!
Iron Lung does have end credit scenes. Stay until the very end!
See current US streaming, rental, and purchase options for Iron Lung (2026) via JustWatch.
Explore the complete cast of Iron Lung, including both lead and supporting actors. Learn who plays each character, discover their past roles and achievements, and find out what makes this ensemble cast stand out in the world of film and television.

Seán McLoughlin
Jack

Elle LaMont
SM-8 Research Assistant, The Whisper

Rahul Kohli
Additional Voices

Danielle Evon Ploeger
Tow Ship Pilot

Valkyrae
Additional Voices

Troy Baker
David

Alanah Pearce
A Familiar Voice

Mark Fischbach
Simon

Elsie Lovelock
SM-8 Research Lead, The Speaker

Ethan Nestor
Additional Voices

Caroline Kaplan
Ava

Dave Pettitt
The Father

Isaac McKee
Young Simon

Asher Wagh
Children of Eden

Kazuki Jalal
Children of Eden

David Szymanski
David Szymanski
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See how Iron Lung is rated across major platforms like IMDb, Metacritic, and TMDb. Compare audience scores and critic reviews to understand where Iron Lung stands among top-rated movies in its genre.
Iron Lung delivers a distinctive, claustrophobic vision that sets it apart in the sci‑fi horror niche. The direction and production design craft a visceral, blood‑filled submarine environment, while Markiplier’s performance anchors the narrative with solid intensity. Critics note sluggish pacing and occasional editorial roughness that blunt the film’s tension, yet many viewers find the atmospheric sound design and layered visual cues rewarding on subsequent watches. The net impression is a bold, mood‑driven piece with strong craft elements that shines when revisited, though its deliberate slow burn may deter those seeking immediate thrills.
The Movie Echo Score Breakdown for Iron Lung
Art & Craft
In terms of art and craft, the film exhibits a striking visual identity, using dim lighting and cramped set design to convey claustrophobia. Direction demonstrates growing confidence, delivering effective scares despite occasional tonal inconsistency. Production design’s blood‑saturated aesthetic is immersive, yet editing choices contribute to uneven pacing that weakens overall momentum. Overall, the craftsmanship is solid with room for refinement.
Character & Emotion
When evaluating character and emotion, Markiplier’s portrayal stands out as intense and committed, providing the film’s emotional anchor. Supporting characters, however, receive limited development, leaving their motivations ambiguous. Chemistry between leads feels functional but not deeply nuanced, and flashback sequences that could enrich backstory are sparse. Consequently, performances are strong at the center but peripheral depth remains underexplored.
Story & Flow
The story’s premise—a solitary descent in a blood‑filled submersible—offers originality and a potent sense of dread. Yet pacing drags through extended static sequences, causing momentum to falter and the climax to feel exhausting rather than cathartic. Narrative coherence suffers in the final act, with ambiguous resolution that some viewers find confusing. Overall, the plot is inventive but hampered by sluggish rhythm and unclear closure.
Sensory Experience
Sensory experience is a notable strength, with sound design that amplifies claustrophobic tension through low‑frequency hums and punctuated metallic clangs. The soundtrack’s sparse cues complement the stark visual palette, reinforcing the dread of an endless crimson abyss. Some reviewers note occasional visual distortion that obscures detail, yet the overall audio‑visual cohesion sustains immersion. In sum, the sensory elements effectively heighten the film’s horror atmosphere.
Rewatch Factor
Rewatch factor is elevated by the film’s layered construction; subtle visual cues and thematic repetitions become clearer on subsequent viewings. The slow, contemplative pace rewards patient audiences, revealing additional narrative texture and reinforcing the oppressive mood. While some may find the initial sluggishness off‑putting, the lingering sense of unease ensures the experience remains memorable. Consequently, repeated watches enhance appreciation of its atmospheric depth.
54
Metascore
7.3
User Score
%
TOMATOMETER
0%
User Score
70
%
User Score
Read the complete plot summary of Iron Lung, including all major events, twists, and the full ending explained in detail. Explore key characters, themes, hidden meanings, and everything you need to understand the story from beginning to end.
In a distant future, a cataclysmic event known as the Quiet Rapture severs all contact with colonized planets—star systems vanish, and humanity is reduced to a fraction of its former size. The story centers on Simon [Mark Fischbach], who is imprisoned for his role in the destruction of Filament Station. His punishment is to test and pilot the SM-13 submarine, nicknamed the Iron Lung, on a perilous mission: descend into an ocean of blood on a moon called AT-5 and return with proof that will grant him freedom if he survives. The sub is welded shut, the porthole sealed, and Simon’s only window to the outside world is a crude camera, with limited radio communications sparking frail contact with the surface.
As the dive begins, the sub’s sensors register movement outside, and Simon captures images of a skeletal figure on the ocean floor. Officials pull him up to review the find, then send him back down to collect a sample from the skeleton. Frustration gnaws at Simon—he wants out—yet he complies, only to discover that the “camera” is an X-ray device that irradiates the crew as it records. The return to the depths uncovers more unsettling truth: the mission is not what it seems, and the crew he thought he might save is suddenly endangered by the very instrument meant to document the discovery.
Down in the blood-soaked unhollows of AT-5, Simon uncovers audio logs from another pilot, proving he was misled about being the first to reach such depths. He attempts to inform Ava [Caroline Kaplan] of his strange sighting—an image of a living creature—but she urges him to press on and secure a sample. As he advances, the submarine fills with blood and an unidentified liquid, seeping into joints and circuitry, and his sense of reality begins to fray.
The isolation intensifies when Simon is knocked unconscious during the sampling. He awakens inside the sub to find movement in the camera feed, and he works to repair the vessel while fighting vivid hallucinations that threaten to erase his grip on reality. A wrecked submarine labeled SM-8 looms in the sonar, and its black box data remains inaccessible. A mysterious female voice speaks through the radio about a godly light beneath the ocean—an encounter that may be only a hallucination. In a nightmarish vision, the sub is destroyed, and Simon bursts to the surface to confront a vast eye filling a stormy red sky.
He returns to consciousness with Ava’s voice explaining that he has been missing for days—far beyond what his oxygen could have sustained. She commands him to recover SM-8’s data, promising to rescue him if he cooperates. Meanwhile, the interior of the Iron Lung fills with blood and fleshy matter, and the strange liquid begins to alter Simon’s skin, signaling that his body is mutating as the mission wears him down.
Reaching SM-8, Simon retrieves its data and uncovers a terrifying revelation: the blood ocean and its creatures are composed of the congealed remnants of humanity, a collective hive mind bent on absorbing any surviving humans. The weight of the discovery crushes him as the sub continues to fill with more organic matter. Ava cannot rescue him, she apologizes, and begs him to safeguard the SM-8 data because it may be humanity’s last hope. At the same time, the enigmatic voice urges him to destroy the data so that no one learns of the light beneath the waves. Before long, a hivemind creature destroys Ava’s vessel, severing the direct line of rescue.
With the sub’s corridors clogged by growths and the hull threatened by pressure, Simon tapes the black box data to a life vest and sabotages the Iron Lung, ensuring a catastrophic failure when the pressure builds. The vessel implodes after a final bite from the sea-born creature, killing both it and its pilot. An observer later discovers the life vest adrift in the blood ocean, the black box still intact, a chilling testament to the mystery that still lingers beneath the waves.

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