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This article is about the Sea Emperor Leviathan. If this is not what you are looking for, see Sea Emperor Leviathan (Disambiguation).
This article is about the Sea Emperor Leviathan. You may be looking for the Sea Dragon Leviathan.


The closest translation of the alien symbol for this specimen is 'sea emperor'. Bone samples from deceased leviathan specimens indicate some potential for Kharaa immunity. Single specimen captured for study at purpose-built emperor containment facility, constructed in volcanic region at depth 1200m.

― PDA, Data Downloads


The Sea Emperor Leviathan is the largest of the living Leviathan class fauna found within the crater in Subnautica. It is sapient and telepathic, but unlike most Leviathans, it is not aggressive.


The Sea Emperor Leviathan is colossal, having a stocky, entirely armored body and is predominantly pale brown in color, with shades of green. Its tentacles are adorned with bright cyan bioluminescent "bulbs."

The creature's head is comparatively small, and quite peculiar in shape (see "Trivia" below for more), featuring two striped antennae with glowing green lures atop its snout, two large mandibles on each side of its rather small mouth, and a glowing hollow between these mandibles. It has four binocular eyes, glowing cyan in color.

The Sea Emperor Leviathan's posterior consists of seven long, yet slim tentacles ending with large tentacular clubs, with the largest being in the center, surrounded by the six smaller tentacles.

Unlike the Sea Dragon Leviathan, the Sea Emperor Leviathan doesn't have true graspers; instead, its forelimbs are two massive, paddle-like arms, similar to some paddles used by turtles, primarily used for stabilization while swimming and possibly used for defense against predators.

It also has a hole in the back with an unknown purpose, most likey for creating enzyme 42 or laying eggs.


Despite its gargantuan size, the Sea Emperor Leviathan's diet consists solely of micro-organisms filtered from the water, much like real-life Baleen whales and Blue whales.

It's suggested that in the past these creatures would have traveled in small herds in the bottom of the trenches (that being the Crater Edge), occasionally coming to the surface to feast on the microorganisms in the shallower water. When the Kharaa Bacterium was released onto the planet, many creatures died, destroying the food source of the species.

The Sea Emperor Leviathan is capable of telepathic speech, which it uses to communicate with the player at various locations around the world. Whenever it communicates with the player, the screen becomes distorted in a similar way to when a Warper teleports the player, or a Mesmer hypnotizes the player.

The Sea Emperor Leviathan will first contact the player telepathically either sixty minutes after attempting to deactivate the Quarantine Enforcement Platform or twenty minutes after reaching the Disease Research Facility (whichever happens first). It will contact the player again shortly after they have obtained the Blue Tablet, and again upon entering the Lava Lakes. It will continue to interact with the player upon entering the Aquarium, telling them what they need to do in order to hatch the eggs. After the player inserts an Ion Cube into the Incubator Device, the Sea Emperor Leviathan will speak to the player, and will move to the left side of the Alien Arch, and blow away the sand, uncovering the Arch that the player can use to access the Arch outside of the Quarantine Enforcement Platform.

Upon entering the aquarium, the Sea Emperor Leviathan will climb up onto a platform to observe and speak to the player, then descend back down. It will also watch the player intently if they are near the Incubator Device or the aquarium Arch, quickly spinning around and coming to a rest on the aquarium's floor.


The captive Sea Emperor Leviathan is the last remaining adult of its species and a parent to at least seven eggs. The five eggs which still remain must be hatched at some point in the story. The creature is approximately two-thousand six-hundred years old, having massively surpassed its species' natural lifespan. It is possible that the Aquarium has some form of life support system in place that allowed the captive Sea Emperor Leviathan to live to such an advanced age, as it was noted that one-thousand six-hundred was already old.

Almost all of the Sea Emperor Leviathans died when the Kharaa Bacterium was released as it killed off their food source, leaving only the one captive adult and the eggs it was discovered with. As the only source of Enzyme 42 on Planet 4546B, the Sea Emperor Leviathan and its children are the keys to cure the Kharaa Bacterium.

The Precursors studied the last surviving Sea Emperor Leviathan in hopes of finding a cure using its natural production of Enzyme 42. However, due to its weakness, possibly old age or illness, studies conducted showed that it was not a viable source of Enzyme 42 as the enzymes it produced was too unstable and only reverted symptoms temporarily. After the Precursors could not find a way to hatch its eggs naturally, they took three into the dissection room of the Primary Containment Facility and experimented on them, cutting all of them open and removing the fetus from one of the eggs. One other egg was taken to the egg lab, where it was also tested on. Still, they could find no way to cause the hatching process to trigger naturally, and juveniles born outside of the natural conditions could not produce suitable enzymes. They resorted to attaching the eggs to an Incubator Device to keep the eggs alive while they worked on more ways to hatch them. Shortly after this, the Disease Research Facility was destroyed, releasing the Kharaa Bacterium, causing all Arches to the facility to be closed and initiating the planetary quarantine.

At an unspecified time, the Sea Emperor Leviathan managed to train Peepers to use the Alien Vents to distribute Enzyme 42 to the surface. Under the Sea Emperor Leviathan's control, Peepers traveled through the Alien Vent, bringing flora seeds to the aquarium, and leaving with small amounts of Enzyme 42 which they distribute at the surface. This system allowed a small amount of life to survive on the planet.

After its eggs are hatched, the captive Sea Emperor Leviathan will play with its children and then direct them to the Arch leading just outside the Quarantine Enforcement Platform which they will leave through. The captive will begin dying shortly afterward, as it has used the last of its strength to play with its babies.[1]


Telepathic Contact Dialogue

Aquarium Telepathic Contact Dialogue

Are you here... to play?
Others came here once. They built these walls.
They played... alone. They bored me.
Now they're gone. And instead... we have you.
We are curious whether you swim with the current, or fight against it as they did.

My young want to hatch.
To play outside this place.
We have been here so long.
The others built a passage to reach the world outside.
I asked them for this freedom, but they could not hear me.
If you help us, I will give you freely what the others tried in vain to take.

With the passage you have opened my young can leave this place.
But first they must feel the time is right and break free of their shells.
This is what the others could not force from me.
To you, I give the secret willingly.

My young are swimming for the shallows. I thank you.
Their freedom is my end.
What will it be like, I wonder, to go to sleep and never wake up?
Perhaps next we meet I will be an ocean current, carrying seeds to a new land...
Or a creature so small it sees the gaps between the grains of sand.
Farewell, friend.

End Sequence Dialogue

What is a wave without the ocean?

A beginning without an end?
They are different, but they go together.
Now you go among the stars, and I fall among the sand.
We are different.
But we go... together.

Data Bank Entries



1. Feeding & Digestion
Alien research data indicates that despite its size this species feeds entirely on microorganisms it filters from the water, which themselves depend on a complicated ecosystem of plant and animal life.

2. Reproduction
Large, ovary-like organs are carried in the creature's middle section, suggesting that like other species on this planet it produces eggs, however internal scar tissue indicates probable infertility.

3. Enzyme 42
The emperor manufactures Enzyme 42 within its stomach cavity to break down its food, and will occasionally expel it into the surrounding waters. This substance was found to neutralize the effects of the bacterium, and its presence in the ecosystem today would explain how life on the planet survived the outbreak. It would remain to be explained by what mechanism the enzyme is being delivered.

4. Health
Comparative analysis of size and metabolic rates indicates the specimen captured by the researchers was approximately 1,600 years old. Extensive internal and external scar tissue suggest it had lived well in excess of the peak lifespan for its species.

Assessment: While a healthy emperor specimen may have held some potential as a cure, it is unlikely any research subjects survived quarantine procedures.

Available biological data has been used to synthesize the effects of the alien bacterium on the sea emperor's natural lifecycle.

This creature likely lived and moved in small herds around the planet's ocean trenches, coming to the surface to feed off the huge volumes of microorganisms in the shallower waters. Family size would be strictly limited by available food supply. Offspring would likely split off at a young age to form their own herds elsewhere.

Given their sparse population, mating and egg-laying were likely infrequent, perhaps a once in a lifetime event. The species likely had a preferred environment for egg-laying - in fact, successful hatching may depend on such conditions. Given the rarity of this event, it is impossible to calculate those conditions precisely.

There is no evidence to support the assumption that all members of the species were immune from the alien bacterium. Even if this is so, there is evidence that introduction of the bacterium decimated life on the planet, and this would have had catastrophic effects on the emperors' food supply and survival rate.

The symbiotic relationship between this specimen and other lifeforms likely developed as a direct result of the bacterial infection. Those lifeforms which learned to keep the emperor alive survived with its help. This may explain the vast tracts of lifeless ocean in a rough perimeter around the emperor's location.

A catalog of information on the organisms previously contained within the alien facility. A number of entries have been translated.

Small Herbivore Gamma:
This entry seems to reference the common peeper. Shows no immunity to infection - death commonly occurs within 4 days. Shows symptom remission on exposure to Enzyme 42, but symptoms quickly recur. Shows advanced learning behaviors. Shows some capacity to transmit enzymes to other specimens.

Leviathan Embryos:
Adult specimen too large to study in containment. Egg specimens acquired from nesting site. Embryos show no signs of immunity - death commonly occurs within 3 weeks. Small sample of eggs has been retained for continued, high priority research on leviathan hatching mechanisms.

Large Carnivore Theta:
Off-site lab established to study remains. Shows some potential for immunity to infection, but physical remains so far proved insufficient for full reconstruction.

Unidentified Leviathan:
This leviathan species has been assigned designator 'Sea Emperor'. Bone samples from emperor specimens indicate some potential for kharaa immunity. Single specimen captured for study at purpose-built containment facility, constructed in volcanic region at depth 1.4km.

Assessment: While it is unlikely that the emperor specimen is still contained within the facility described, it may be possible to acquire further data there on the aliens' attempts to develop a vaccine.


Main article: Achievements
Spoiler alert: The following section contains story related material.
OptimalHealthAchievement.png Optimal Health

Cure the infection

How to obtain: The player must communicate with the Sea Emperor Leviathan and hatch the Sea Emperor Infants in order to obtain Enzyme 42. The player must complete the entire healing cutscene in order to obtain the achievement.



  • The Sea Emperor Leviathan's dialogue suggests that the species are philosophical, if not religious. It references a concept similar to reincarnation by saying "Perhaps next we meet I will be an ocean current, carrying seeds to new lands... or a creature so small it sees the gaps between the grains of sand".
    • This dialogue also suggests a great understanding of the natural world on the part of the Sea Emperor, as it understands what an ocean current is and the roles they play in nutrient distribution in the oceans.
  • Early concept art of the Sea Emperor Leviathan depicted it with large, clawed graspers on the ends of its arms, resembling those of a Sea Dragon Leviathan. This idea was later replaced by the paddle-like limbs they now have.
    • Despite being depicted significantly smaller than the Sea Dragon Leviathan in concept art, the Sea Emperor Leviathan was always intended to be the largest creature in Subnautica.
    • The Sea Dragon Leviathan was created as an aggressive reskin of the Sea Emperor Leviathan.
  • The Sea Emperor Leviathan's dialogue suggests that the Precursors were unable to "hear" its telepathy, as they did not hear its pleas to let its young go free.
  • Certain developmental notes refer to the Sea Emperor Leviathan as the "Emperor Leviathan", and refer to added animations to "bite" and "attack".[2]
    • Various documents also refer to the Sea Emperor Leviathan as the "Grand Leviathan".
    • All Sea Emperor sound files exist within the folder "Magistrate", suggesting another developer name. This folder also contains roar sounds, which are higher-pitched versions of Reaper Leviathan roars, which further suggest that the Sea Emperor was at one point aggressive.
  • The Sea Emperor Leviathan closely shares many of its features with real-life animals: a head shape slightly similar to that of many hammerhead sharks, and paddle-like arms, resembling those of the green sea turtles.
  • The opening sentence of the databank entry suggests that Sea Emperor Leviathans are the largest living species identified in the Subnautica universe.
  • It is possible that the Sea Emperor Leviathan attempted to communicate with Bart Torgal, as he had described seeing visions before his death, presumably the same visions that Ryley Robinson had received during his explorations.
  • It is currently impossible to scan the Sea Emperor Leviathan, and as a result, it does not have a fauna databank entry. Instead, the entry is obtained from a Precursor terminal.
    • It is also impossible to attack the Sea Emperor Leviathan.
  • The Sea Emperor Leviathan species is the only known complex fauna species on 4546B known to reproduce asexually, in contrast to other known species which reproduce by sexual reproduction as they are simultaneous hermaphrodites, excluding simple fauna species such as the Amoeboid which reproduce via longitudinal fission.