Subnautica's Story Explained

Subnautica's story starts simple: man is stuck on alien world, he'd rather not be on alien world. It's a universal tale for the ages we can all get behind and understand. However, it's not long before that simple narrative twists into something bizarre, involving strange diseases, alien races, and at least three different spaceship crashes. Fortunately, we're here to explain the plot, taking you through it step by step.

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The Backstory of Subnautica

Most of Subnautica's plot actually happens before you get there, a background mystery that reveals itself as you explore and interact with its wide, weird world. Consequently, the major players are never even seen or heard from, even though they set so much in motion.

The Precursors and Kharaa

Roughly a thousand years ago, an alien species called the Precursors were exploring various worlds when they contracted a bacterial disease called Kharaa which caused them to sicken and die. Desperate for a cure, the Precursors spread across the galaxy, researching different life forms in the hope of finding some basis for a cure or vaccine.

Planet 4546B and the Sea Emperor Leviathan

The Precursors eventually struck gold when researching an ocean world we'd come to know as Planet 4546B. The largest lifeform on that world, a huge telepathic species called the Sea Emperor Leviathans, produced a chemical called Enzyme 42 that effectively made them immune to the deadly Kharaa. The Precursors trapped a female Emperor in a building called the Primary Containment Facility, and stole seven of her eggs for experimentation, hoping to extract this precious enzyme.

The Failed Experiment and the Leviathan's Eggs

Unfortunately for the Precursors, the Emperor Leviathan they kidnapped couldn't help them. Its old age meant that the Enzyme 42 it produced wasn't potent enough to actually cure them of the Kharaa, only mitigate its effects for a while. They tried to force two of the eggs to hatch prematurely, hoping to harvest a fresh supply of the drug, but only killed the embryos in the process, unable to hear the telepathic pleas of the Emperor telling them that this wouldn't work and that the eggs couldn't hatch on command like they wanted.

The Dragon Attack and the Release of the Kharaa

Realising their mistake, the Precursors tried a new tactic, this time stealing an egg from a similar species called the Sea Dragon Leviathan, hoping it would be genetically close enough to provide the cure they needed.

They never got the chance to find out. Emperor Leviathans were peaceful, intelligent creatures, but Dragon Leviathans were massive, deadly hunters, and the egg's parent attacked the Disease Research Facility in a furious attempt to get its child back. The facility was damaged and Kharaa was released into 4546B's oceans, effectively contaminating the world. The Precursors realised that they couldn't stay safely in such an environment and fled, declaring a worldwide quarantine and leaving behind a giant gun turret called the Quarantine Enforcement Platform, designed to automatically shoot down any ships entering or leaving the atmosphere, all in an attempt to prevent the Kharaa from spreading further than it already had.

The Devastation of Planet 4546B

The spread of Kharaa nearly destroyed the planet. Most of 4546B's species were killed by the Kharaa, and many others died as a result of losing their food sources to infection, including every Sea Emperor Leviathan except for the one imprisoned in the Primary Containment Facility.

Unable to escape and horrified at the destruction, the Emperor tried to mitigate the damage by telepathically training the little Peeper fish that swim in and out of the facility to distribute Enzyme 42 across the planet. It wasn't enough to kill the Kharaa infection, but it gave some lifeforms enough time to evolve and mutate into new species that could survive in this vastly altered biosphere. Abandoned and damaged by the Precursors, Planet 4546B would remain silent for nearly a thousand years, trying to recover from what had been done to it.

Crash of the Degasi

Hundreds of years later in the late 22nd Century, humanity has colonised space when a small ship called the Degasi flies too close to Planet 4546B and is promptly shot down by the automated Quarantine Enforcement Platform, still functional after all this time. Three of its crew of six die in the crash and the rest are stranded, one of their number being an important Mongolian CEO named Paul Torgal. The three survivors contract Kharaa and are killed in various horrible ways before they can call for help or make an escape, either getting attacked by ocean monsters or succumbing to the disease.

Crash of the Aurora

You'll never guess what happens next. Ten years after that, a huge spaceship called the Aurora is flying through the same area, allegedly to build something called a Phasegate, but in reality it's secretly there to look for the remains of Torgal and the Degasi. Again, the Quarantine Enforcement Platform shoots down the Aurora, and this is where we enter the story, playing a minor engineer named Ryley Robinson who survives in an escape pod and must try to find a way off-world.

The Plot of Subnautica

At this point we'll be going over the main events that take place in the game, either those implied or seen directly by the player.

Crash of the Sunbeam

Yes, it happens yet again - soon after the crash, a ship called the Sunbeam radios Ryley and promises to come in to help, only to be shot down by that damn Platform, killing all on board and making it clear to the player that if you ever want to leave, you have to shut down those guns first. At the same time, Ryley begins to discover the abandoned technology and buildings of the Precursors and receive telepathic messages from the trapped Emperor Leviathan. He also discovers that he's infected by the Kharaa, meaning that he can't leave without curing himself first, partly to stop spreading the infection, but also because the Quarantine Enforcement Platform won't allow access to anybody who's infected.

Meeting the Emperor and Discovering the Truth

Summoned telepathically, Ryley finds his way into the Primary Containment Facility and meets the Emperor Leviathan, now over two and a half thousand years old, who asks him to find the stolen eggs and bring them to her along with certain plants that will finally prompt them to hatch. In doing so, Ryley discovers the source of the infection, the history of the Precursors, and just what the hell that big laser is that keeps shooting things out of the air.

Curing the Kharaa and Escaping 4546B

Ryley goes to all four corners of the ocean to get the plants and find the eggs, bringing them back to the Emperor where they hatch at last, releasing a fresh supply of the enzyme that cures Ryley and begins to finally purge the ocean of Kharaa. The babies leave the facility, their mother playing with them briefly before starting to die of old age, and Ryley shuts down the Quarantine Enforcement Platform, allowing him to escape with a rocket he builds from schematics left on the wreckage of the Aurora. As he leaves, the Emperor telepathically wishes him farewell with the last of its strength, saying that in a sense, they are both leaving together.

Now that you know what's going on, you'd best know how to do it. If you're early in the game, why not check out our guide on finding Cave Sulfur? Or if you're a little further in, you can see our guide to making titanium ingots and how to use them. Of course, if you want to beetle about the blue as fast as possible, we've explained how to build your own Seamoth Submarine.