Subnautica Story Recap
Complete story recap covering both Subnautica and Subnautica: Below Zero as essential backstory context for Subnautica 2. Covers the Aurora crash, Planet 4546B, the Kharaa bacterium, the Sea Emperor Leviathan cure, Robin Ayou's investigation into her sister's death, Al-An the Architect, and the events leading into Subnautica 2.
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Subnautica story recap
The original Subnautica (released January 23, 2018) follows Ryley Robinson, the Non-Essential Systems Maintenance Chief aboard the Alterra Corporation ship Aurora. This article covers the full plot for players who want background before playing Subnautica 2.
The Aurora
The Aurora is an Alterra Long-Range Capital Ship, roughly 1,280 meters nose to thrusters and 500 meters tall. It carries a crew of 157 across four divisions: 23 command staff, 85 engineers, 40 support crew, and 9 passengers. Its primary mission is phasegate construction in the Ariadne Arm, with a secondary objective to search for the Degasi, a ship that disappeared in the same sector ten years earlier.
Captain Hollister commands the Aurora. As the ship passes near an uncharted ocean planet designated 4546B, an energy beam from the planet's surface strikes the vessel, causing it to break apart. Hollister dies controlling the ship's descent to minimize casualties. Ryley escapes in Lifepod 5 and is the sole survivor on the planet's surface.
Surviving crew and lifepods
The Aurora carried 50 lifepods. Twenty-five managed to deploy before the crash; the rest were inoperable. Players can locate the wreckage of lifepods 2, 3, 4, 7, 12, 13, 17, and 19 during exploration, each containing audio logs that piece together the fates of their occupants.
Lifepod 2 Contained CTO Yu and crew member Berkeley. Crashed 500 meters deep in the Northern Blood Kelp Zone. Both drowned attempting rescue dives.
Lifepod 4 Landed in Reaper Leviathan territory near the Aurora's bow. One of the few pods with functioning flotation. The occupant sent a final distress call before being attacked.
Lifepod 7 Located in the Crag Field. Contains a Markiplier bobblehead Easter egg. The pod's fabricator malfunctioned, producing hats and lab equipment instead of survival tools. The occupant was killed by Bonesharks.
Lifepod 12 Contained crew member Danby, who had fraudulently passed his medical exams. Crashed in the Bulb Zone. Danby contracted the Kharaa bacterium and documented his deteriorating condition in his logs.
Lifepod 13 Carried Mongolian Emissary Jochi Khasar. Hit the ocean at terminal velocity in the Northwestern Mushroom Forest. No survivors.
Lifepod 19 Contained Second Officer Keen, who assumed command after Hollister's death and broadcast rendezvous coordinates to all survivors. Keen landed in the Deep Sparse Reef, became infected with Kharaa, and was killed by Warpers.
Planet 4546B
The planet is almost entirely ocean. Ryley discovers the remains of the Degasi crew through abandoned bases and audio logs scattered across multiple biomes. The three Degasi survivors (Paul Torgal, his son Bart, and mercenary Marguerit Maida) had been stranded for years, eventually building habitats at increasing depths. Paul and Bart died. Marguerit survived alone in the deep ocean.
The Kharaa bacterium
Ryley becomes infected with the Kharaa Bacterium, an alien pathogen that had devastated the planet's ecosystem. The Architects (also called Precursors) brought the bacterium to 4546B for study. A containment breach at one of their research facilities released it into the ocean, infecting the local wildlife and ultimately killing the Architects who remained.
The Quarantine Enforcement Platform
The Architects built the Quarantine Enforcement Platform (QEP) on the planet's surface to prevent any infected organisms from leaving. The QEP shot down the Aurora, and when a rescue ship called the Sunbeam attempts to land, the QEP destroys it too. Players receive radio transmissions from the Sunbeam over the course of about three weeks, culminating in the ship's arrival at Mountain Island. Even if the player manages to disable the QEP before the Sunbeam arrives, the crew cannot land due to orbital debris from the Aurora wreck.
The Sea Emperor Leviathan
Deep underground, in the Primary Containment Facility at approximately 1,200 meters depth in the Lava Lakes biome, Ryley discovers the Sea Emperor Leviathan, the last surviving member of its species. The Architects captured it centuries ago after discovering it produced Enzyme 42, the only known cure for the Kharaa. However, the adult's enzyme was too unstable to synthesize at scale. The Sea Emperor's five unfertilized eggs held the key, but the Architects could not get them to hatch.
The Sea Emperor communicates with Ryley telepathically throughout the game, first as vague visions and later as coherent speech. It is over 2,600 years old and has outlived its species' natural lifespan by centuries.
The cure and escape
Ryley crafts a batch of hatching enzymes using seeds from four plants accessible through the facility's Alien Arch teleporters, plus a Sea Crown from the containment chamber. All five eggs hatch. The baby Sea Emperors release stable Enzyme 42 into the ocean, curing Ryley's infection and beginning the planet's ecological recovery. The adult Sea Emperor, having fulfilled its last purpose, dies shortly after playing with its offspring.
With the infection cured, Ryley disables the QEP and builds a rocket (the Neptune Escape Rocket) to leave the planet. He reaches Alterra space and receives a message informing him that he owes Alterra approximately one trillion credits for the resources he consumed during his survival. Everything from the food he fabricated to the rocket he built is billed to his account.
Game modes
Survival The default mode. Players manage health, oxygen, food, and water. Death drops items.
Freedom Identical to Survival but hunger and thirst meters are disabled. Focus is on exploration and building.
Hardcore Permadeath with a single life. The PDA does not warn players about low oxygen.
Creative Full sandbox. The player is invincible, resources are not consumed when crafting, and vehicles need no energy.
Commercial performance
Subnautica sold over 5.3 million copies and generated more than $108 million in Steam revenue. It spent about three years in Early Access (December 2014 to January 2018) and was widely praised for its blend of exploration, survival mechanics, and environmental storytelling. The game was built in Unity.
Subnautica: Below Zero story recap
Subnautica: Below Zero (released May 14, 2021) is set two years after the events of the original Subnautica. It follows Robin Ayou, a scientist who travels to Planet 4546B to investigate the death of her sister Sam.
Robin's arrival
Robin smuggles herself onto the planet without Alterra Corporation's knowledge. Her official cover is as a researcher at Alterra's station in Sector Zero, an arctic region of Planet 4546B. Alterra has returned to the planet after Ryley Robinson's departure and established a research outpost. The Vesper, an Alterra orbital station, monitors operations from geosynchronous orbit, periodically demanding progress reports from personnel on the surface.
Sam's death
Sam Ayou was a roboticist at Alterra's Sector Zero research station. She discovered that Alterra had found a frozen leviathan in the Glacial Basin still infected with the Kharaa bacterium and was studying the pathogen for potential bioweapons applications.
Encouraged by Marguerit Maida (the Degasi survivor from the first game, who had drifted to Sector Zero and built a hidden base beneath the Lilypad Islands), Sam took action. She synthesized a cure using Enzyme 42 and stashed it, then set explosives to collapse the cave housing Alterra's Kharaa specimens at the Phi Excavation Site. Both Sam and security guard Parvan were killed in the resulting cave-in. Alterra covered up the circumstances, ruling Sam's death as "employee negligence."
The Frozen Leviathan
The Frozen Leviathan is a massive creature trapped inside a wall of ice at the Phi Excavation Site in the Glacial Basin. Alterra had built corridors and catwalks around it for research access. The creature is infected with Kharaa. Players can eventually use Sam's hidden antidote cache to cure the leviathan, completing her unfinished mission.
Al-An
While exploring an Architect facility, Robin accidentally downloads Al-An, an Architect consciousness, into her brain. Al-An was a lead scientist who had disobeyed his species' orders by attempting to hatch Sea Dragon leviathan eggs, causing the facility's destruction and triggering the Kharaa outbreak on 4546B centuries earlier.
Al-An is stuck in Robin's head because his physical body was destroyed. The two develop an uneasy partnership over the course of the game. Robin learns about Architect society, their technology, and their relationship with the Kharaa bacterium through conversations with Al-An while they explore Sector Zero together.
Building Al-An's body
Robin constructs a new physical body for Al-An using Architect technology scattered across Sector Zero. The body requires three components, each found at a different Architect Cache site:
Architect Organs Found in the Crystal Caves Cache, stored in an open container.
Architect Skeleton Found in the Deep Lilypads Cave Cache, in front of an Alien Statue.
Architect Tissues Found in the Arctic Spires Cache, buried under collapsed rubble.
Once collected, Robin fabricates the complete vessel at the Fabrication Facility deep in the Fabricator Caverns, accessed through the Crystal Caves.
Marguerit Maida
Marguerit is a Trans System Federation veteran and mercenary who was originally hired by Paul Torgal to guard the Degasi. She was one of three Degasi crash survivors (with Paul and his son Bart) and the only one still alive a decade later. She likely survived the Kharaa infection through bioaccumulated Enzyme 42 from the Reaper Leviathan she fought.
By the events of Below Zero, Marguerit has built a base below the Lilypad Islands and maintains a greenhouse on a nearby iceberg. She is hostile to Robin at first but gradually assists her. She was the one who encouraged Sam to sabotage Alterra's Kharaa research, making her indirectly responsible for both Sam's and Parvan's deaths.
Resolution
Once Al-An's new body is complete, he transfers out of Robin's brain and into the physical form. He decides to return to the Architects' homeworld. Robin, having burned her bridges with Alterra, chooses to travel with Al-An rather than return to human space. The game ends with them departing 4546B together.
The story rewrite
Below Zero's story underwent a complete overhaul partway through Early Access. In November 2019, Unknown Worlds announced they were scrapping the original narrative and hiring writer Jill Murray to start fresh. The team stated they had struggled to "define characters' motivations early and build key relationships."
The original Early Access story kept Sam alive aboard the Vesper orbital station, with Robin stationed on the planet surface. The rewrite killed Sam before the game begins and shifted Robin's motivation from a routine research assignment to a covert investigation into her sister's death. The change to a voiced, opinionated protagonist was itself controversial within the community. Voice actress Kimberly Brooks replaced the original Early Access performer Tala Gouveia, who was unavailable to return.
Development notes
Below Zero was originally planned as DLC for the first Subnautica but was expanded into a standalone game. It entered Early Access on January 30, 2019 and launched in full on May 14, 2021. Like the original, it was built in Unity.