Six Ghost Leviathans spawn on the map (not counting the three found in the Crater Edge): three juveniles in the Lost River, two adults in the Grand Reef, and one adult in the Northern Blood Kelp Zone.
If the player enters the Crater Edge, a single adult Ghost Leviathan spawns in. If the player stays in the Crater Edge for thirty seconds, a second Ghost Leviathan will spawn. If the player stays in the area for another thirty seconds, a third and final Ghost Leviathan spawns in. They will all pursue the player until the player returns to the playable area, upon which they will all retreat.
The Giant Cove Tree is the nesting ground of this leviathan species (although they are not present around the tree), with its massive glowing bulbs being their eggs which are blue and purple. According to PDA scan entries of the Cove Tree, the eggs were laid there when the tree was small, and the branches have grown around the eggs to protect them until conditions are right to hatch. The Ghost Leviathans' life cycle begins in the Lost River, as juveniles. As the leviathans mature and become too large for their home, they migrate to the open, surface world biomes such as the Grand Reef and Blood Kelp Zone, until eventually migrating to the Crater Edge, continuing to grow and roam freely in the open water. Despite being much smaller than the Sea Emperor Leviathan, the Ghost Leviathan's eggs can be far larger, capable of growing to sizes far too large for the creature to lay, suggesting the eggs can grow in size after being laid. Since the leviathans in the Crater's Edge are able to survive there, it can be assumed that Ghost Leviathans can feed off of microscopic organisms.
The Ghost Leviathan has a soft, bioluminescent, transparent outer membrane covering a muscular, blue, inner body which features many darker blue stripes, 12 yellow, bioluminescent eyes as well as six, possibly vestigial fins on the torso section. A small, decorative sail sits on top of the head, and two long structures protruding from either side of its head which bear similarities to the cephalofoil of a hammerhead shark. It has a rectangular mouth with a glowing barbule lure beneath. Its long body tapers to a point.
The outer body is transparent, making the smaller, inner body visible. The inner body is long and thin, and covered in pulsating, bioluminescent orange stripes with many orange tipped protrusions ending with blinking bioluminescent orange glows. Unlike the outer body, the inner body has a distinct, thin neck joining the head and body. As the leviathan moves through the water, it leaves trails behind it.
To attack a target, it will spiral up and charge. When charging, it will open up its mouth and make a loud, echoing screech. If it successfully attacks, it will do 84% damage to the player and swim some distance away, as if losing interest.
Adults are able to push the Cyclops and either drag it, or overturn it. If the player is walking around the Cyclops when the Adult begins to push (for example, if they are trying to put out fires caused by an attack), and the Leviathan rolls the submarine over, the player can be killed instantly upon colliding with the walls or ceiling.
Data Bank Entries
This creature is approaching the size limit for sustainable organic lifeforms, and has been designated leviathan class. Adults of the species have been encountered exclusively around the edges of the volcanic crater which supports life on this part of the planet, and react with extreme aggression on approach.
Assessment: Extreme threat - Avoid the crater edge
This large predator has adapted to live in deep waters and dark cave systems, attacking anything and everything in its quest to grow larger.