The Sea Dragon Leviathan is a colossal leviathan class fauna species. It is the largest aggressive creature of Subnautica. There are a total of three Sea Dragon Leviathans on the map: two in the Inactive Lava Zone and one in the Lava Lakes.
The Sea Dragon Leviathan's body mostly resembles the Sea Emperor Leviathan, albeit much smaller and slimmer in design. The body is mostly 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 Sea Dragon is stout and reptilian, possessing two pairs of glowing orange eyes with white pupils, a crack-like pattern spreads from the pupils to the rest of the eye. The mouth contains a pink tongue and thirty-two 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 approximately equal in size to the player's 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, the largest tentacle being surrounded by the six smaller ones.
The Sea Dragon Leviathan uses its arms and tentacles to swim in the water at great speed; according to the "Damaged Anchor Cable" entry from the Disease Research Facility, it is capable of exerting over 300 tons (600,000 pounds) of force by ramming. Just being in close proximity to the Sea Dragon Leviathan will cause the player or Prawn Suit to be jostled due to the water it displaces. 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 even if the player has the Reinforced Dive Suit equipped. 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. The Sea Dragon Leviathan can deal massive damage to a Prawn Suit very quickly; the swat attack does 11% damage to the suit, the Sea Dragon Leviathan also has the ability to grab the vehicle in its mouth and deal 10-20% damage before releasing it; it often swats immediately after. A sustained barrage of small fireballs, known as the Fire Breath attack, can deal lots of damage in a short time to the Prawn, it'll often swat the vehicle soon after and do this again if you're still in the vicinity.
When the Sea Dragon Leviathan is exposed to damage, it will flinch and commonly, if the Player is close, it will swat them away dealing large amounts of damage to the Player if they aren't in any Vehicles. The Sea Dragon Leviathan will get stuck inside the walls of the map, but still be able to attack the player. Similar to the Lava Lizard, the Sea Dragon is completely resistant to the Thermoblade.
The entire life-cycle of the Sea Dragon Leviathan is almost exclusive in the Inactive Lava Zone and Lava Lakes only leaving their natural habitat in order sustain their food supply by hunting Reaper Leviathans in the shallower waters. Other than Reaper Leviathans, they consume the Crimson Rays or Lava Lizards when fully grown and presumably Lava Larvae and Magmarang and Red Eyeye when born.
Spoiler alert: The following section contains story related material.
A little under a thousand years ago, a Sea Dragon Leviathan Egg was taken by the Precursors and contained within the Disease Research Facility for testing, however, the parent Sea Dragon pursued the Precursors back to the facility and destroyed it, resulting in the Kharaa 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.
Data Bank Entry
A colossal leviathan with reptilian features, seen stalking the very heart of the volcanic crater which underpins life in this area. The scanned specimen measured 112m in length.
1. Heat-Proof Tissue:
The sea dragons' size and the restrictions of the cave systems they inhabit suggest their population numbers are extremely low, perhaps in the single digits. While it is not unusual for larger predators to sustain lower populations, it is possible the sea dragon's food sources have diminished over time. This species may be nearing extinction.
Assessment: Extreme threat - Avoid in all circumstances
- The sounds of the Sea Dragon Leviathan were created by combining real sounds from a bull, an elephant, and a tiger.
- The Sea Dragon Leviathan was originally larger than it is currently, the downsizing being due to a bug that was ignored for several months. The developers ultimately decided to leave it at its incorrect scale since no one remembered its original size, and also because it already had problems navigating terrain. However, it currently seems to line up with the 112 m statistic.
- The Sea Dragon Leviathan used to be able to attack the Seamoth, but due to the developers figuring out that the Seamoth couldn't go that deep, they removed it.
- The Sea Dragon Leviathan's size may be caused by deep sea gigantism, a phenomenon where deep-sea dwelling animals tend to be significantly larger than creatures that live in shallower waters.
- This would also explain the Sea Dragon's eating habits; a lack of food in deeper waters is a theorized explanation for deep sea gigantism, as Kleiber's Law states that metabolic efficiency scales with size, giving larger creatures an advantage in deep-sea conditions where food is scarce. Some creatures thought to have undergone deep sea gigantism can go up to 5 years without eating, making it possible that Sea Dragons only come up to hunt Reapers every few years.