This article is about the Sea Emperor Leviathan. You may be looking for the Sea Emperor Juveniles or the Sea Emperor Babies.
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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 living species of fauna known in Subnautica.


The Sea Emperor Leviathan is colossal in size, having a stocky, entirely armored body and is predominantly pale brown in color, with a few 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 in-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, which are similar to those of a sea turtles.


Despite its gargantuan size, the Sea Emperor Leviathan's diet consists solely of micro-organisms filtered from the water. 

It is suggested that in the past these creatures would have traveled in small herds, 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 the player enters an Alien Arch.

The Sea Emperor Leviathan will first contact the player telepathically twenty minutes after they have attempted to deactivate the Quarantine Enforcement Platform. 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 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 still remaining must be hatched at some point in the story. The creature is approximately one thousand six hundred years old, having massively surpassed its species' natural lifespan.

Almost all of the Sea Emperor Leviathans died when the Kharaa Bacterium was released as it killed off their food source, leaving 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 key to cure the Kharaa Bacterium.

The last surviving Sea Emperor Leviathan was studied by the Precursors 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 whilst 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

What... are... you?###2000

Emperor Telepathic Contact1

Come here, to me.###5000

Emperor Telepathic Contact2

I am what... you seek. Want to... help you.###5000

Emperor Telepathic Contact3

Aquarium Telepathic Contact Dialogue

Are you here... to play?###500
Others came here once. They built these walls.###1000
They played... alone. They bored me.###1700
Now they're gone. And instead... we have you.###2000
We are curious whether you swim with the current, or fight against it as they did.###2000

Precursor Prison Aquarium EmperorLog1

My young need to hatch.###1000
To play outside this place.###1000
We have been here so long.###1000
The others built a passage to reach the world outside.###1500
I asked them for this freedom, but they could not hear me. ###1500
If you help us, I will give you freely what the others tried in vain to take.###1500

Precursor Prison Aquarium EmperorLog2


With the passage you have opened my young can leave this place.###1500
But first they must feel the time is right and break free of their shells. ###1500
This is what the others could not force from me.###1000
To you, I give the secret willingly. ###1000

Precursor Prison Aquarium EmperorLog3


My young are swimming for the shallows.###1000 I thank you.###1000
Their freedom is my end.###1000
What will it be like, I wonder, to go to sleep and never wake up? ###1500
Perhaps next we meet I will be an ocean current, carrying seeds to a new land...###1500
Or a creature so small it sees the gaps between the grains of sand.###1500
Farewell, friend.###1500

Precursor Prison Aquarium EmperorLog4

End Sequence Dialogue

What is a wave without the ocean?

A beginning without an end?###1000
They are different, but they go together.###500
Now you go among the stars, and I fall among the sand.###500
We are different.###500
But we go... together.###500

Rocket Emperor

Data Bank Entries



1. (Feeding & Digestion) Despite its size, this species subsists entirely on microorganisms it filters from the water. The mere presence of these microorganisms in such a restrictive environment is highly unlikely, depending as they do on a complicated ecosystem of plant and animal life.

2. (Reproduction) Since just one adult specimen of this kind has been identified, it may reproduce asexually, but it may equally be the last of its kind. Large ovary-like organs are carried in the middle section, suggesting that like other species on this planet it produces eggs, however, internal scar tissue indicates probable infertility.

3. (Stomach Enzyme) The emperor is the only known source of a unique, complex enzyme which seems to play a pivotal role in protecting the ecosystem against the impacts of the bacterium. Peepers appear to have adapted to distribute the enzyme, however, its structure is unstable, and they require a constant supply to stave off uncontrollable genetic mutation.

4. (Health) Comparative analysis of size and metabolic rates indicates this specimen is approximately 1,600 years old. Extensive internal and external scar tissue suggests it has lived well in excess of the peak lifespan for its species.

Assessment: Enzyme too unstable for cure. Enzyme synthesis impossible. One possibility left open: fully vaccinate an individual with a more stable concentration of the enzyme, produced by a healthier specimen.


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.


Analysis of the enzyme-production organs in the sea emperor species indicates that it may be possible to permanently purge the alien bacteria from a human system with a sufficiently stable enzyme sample. Unfortunately, the emperor specimen contained within the alien facility is in poor health and unlikely to produce the enzyme with the necessary strength. A juvenile of the species would provide a higher chance of success.

This device catalogs information on the organisms contained at this facility prior to the bacterium's release into the ecosystem. A number of entries have been translated.

Shows no immunity to infection - death commonly occurs within 4 days. Does show limited symptom remission on exposure to emperor stomach enzymes, but symptoms quickly recur.

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

Shows no immunity to infection. Shows advanced learning behaviors. Shows some capacity to transmit enzymes to other specimens.

Unidentified 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 a volcanic region at depth 1200m.

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



  • 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, I will carry seeds to new lands... or a creature so small it sees the gaps between the grains of sand".
  • 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 arms 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 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".[2]
    • Various documents also refer to the Sea Emperor Leviathan as the "Grand Leviathan".
  • 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.


  2. Dated June 16, 2015.