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. 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. 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. 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. A large sail sits on the creature's back, just below the shoulders. 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. Along the side of its body runs two long trails of small hollows that emit orange bioluminescent glows. It also has a second set of larger fin-like protrusions beneath its lower jaw. The tip of the snout features two short, green protrusions with orange glowing tips. The mouth contains a pink tongue and thirty-two large teeth, visible even when the mouth is closed. 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. Many of its body parts are adorned or spotted with orange bioluminescent glows, and many small spines line its lower jaw and arms. It has protective plates on the underside of its body that start at the neck and run down to where the tentacles begin. The body is mostly dark green in color, along with purple accents on its webbed limbs and head.

The Sea Dragon Leviathan's body mostly resembles the Sea Emperor Leviathan, albeit much smaller and slimmer in design.

Subnautica leviathan skeleton