|This article is about the Sea Dragon Leviathan. You may be looking for the Sea Emperor or Reaper Leviathan.|
The Sea Dragon Leviathan, more commonly known as the Sea Dragon, is a colossal life form belonging to the fauna category. It is also the largest aggressive creature of Subnautica. In total there are three Sea Dragon Leviathans on the map; two in the Inactive Lava Zone and one in the Active Lava Zone.
The Sea Dragon Leviathan's body mostly resembles the Sea Emperor, albeit slightly smaller, slimmer in design, and is dark green in color, along with purple accents on its webbed limbs and head. It has protective plates on the underside of its body that start at the neck and run down to where the tentacles begin. Many of its body parts are adorned or spotted with orange bioluminescent glows, and many small spines line its lower jaw and arms.
The head of the creature is stout and reptilian, possessing two pairs of glowing orange eyes with white pupils, a cracked pattern spreads from the pupils to the rest of the eye. The mouth contains a pink tongue and a few large teeth, visible even when the mouth is closed. The tip of the snout features two short, green protrusions with orange glowing tips. It also has a second set of larger fin-like protrusions beneath its lower jaw. Along the side of its body runs two long, trails of small hollows that emit orange bioluminescent glows. It has two long forearms ending with webbed, four digited hands; each digit ends with a claw that is similar in size to the players entire body. A large sail sits on the creature's back, just below the shoulders. Its rear-side consists of seven tentacles, also lined with orange spots, and ending with small tentacular clubs, with the largest being surrounded by the other smaller ones.
The Sea Dragon Leviathan uses its arms and tentacles to swim in the water at great speed. Just being in close proximity to the Sea Dragon will cause the player or PRAWN Suit to be jostled. It will attack the player with its arms if they are on either side of its front body by swatting them away and dealing 40 damage to the player.
If the Sea Dragon Leviathan attacks the player with its mouth, it will swallow the player, killing them instantly.
Occasionally, the Sea Dragon Leviathan will open its mouth wide and fire a molten rock at its target as a projectile attack. The Sea Dragon Leviathan is also capable of firing a barrage of small "fireballs" covering a wide area.
The Sea Dragon Leviathan will attack the Cyclops by slamming it with its arms with considerable force, often leaving the Cyclops upside down or on its side. However, it cannot damage the Cyclops, only push it around.
The Sea Dragon Leviathan can deal massive damage to a PRAWN Suit very quickly; the swat attack only does 4% damage to the vehicle but often knocks it into lava. The Sea Dragon Leviathan will grab the vehicle in its mouth and deal 10% damage before releasing it; it often swats immediately after. The meteor attack can do between 24% and 48% damage to the vehicle.
A little under a thousand years ago, some Sea Dragon Leviathan Eggs were taken by the Precursors and contained within the Disease Research Facility for testing, however, the mother Sea Dragon pursued the Precursors back to the facility and laid waste to it, resulting in the Carar bacterium being released onto Planet 4546B, causing the Precursors to put the planet into quarantine.
The skeleton of this Sea Dragon Leviathan can be found near the Disease Research Facility, having suffered massive head trauma from the attack.
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A colossal aquatic species with reptilian features. It appears to have evolved to consume molten minerals, and expel these materials as a form of self-defense.
Assessment: Extreme threat
- The Sea Dragon Leviathan may spawn outside of the map borders, in the void, as a means to discourage players from leaving the map. 
For a more complete gallery, visit Sea Dragon Leviathan/Gallery
- While shown in the Concept Art to be considerably larger than the Sea Emperor, the Sea Dragon Leviathan was implemented to be smaller than the latter in a future update.
- The sounds of the Sea Dragon Leviathan were created by combining real sounds from a bull, an elephant and a tiger.
- Several Reaper Leviathan skeletons can be seen in the Inactive Lava Zone, this is due to the infrequent trips Sea Dragons make to the surface in order to hunt Reaper Leviathans and bring them back to their home to feast.
- Its appearance is similar to Otachi, a Kaiju from the film Pacific Rim.