Crater Edge

Subnautica takes place inside the crater of an enormous, dormant, aquatic volcano, two kilometers in diameter. The Crater Edge is the area surrounding this crater. With no resources and extreme danger, the zone serves as a border for the game's map.

Multiple adult Ghost Leviathans live in the Crater Edge, where they deter players from straying outside of the playable area. Up to three Ghost Leviathans can appear at once, only retreating when the player leaves the zone. If the player enters the Crater Edge, a single 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 Crater Edge has a small amount of unfinished terrain at 3000 meters depth. Past that terrain there is another, seemingly infinite drop. After 8200 meters depth, the player (as well as any vehicle being piloted) teleports back to the surface. At approximately 4000 horizontal meters away from the map center, the zone ends. Leviathans cease spawning and there is only empty ocean, acting as the real end of the game's limit.

Description
The Crater Edge is a large open ocean devoid of any flora, coral, and all but one fauna species.

Fauna

 * Ghost Leviathan

Trivia

 * Sea Dragon Leviathans, Reaper Leviathans, and other fauna were planned to spawn in the Crater Edge at one point, but this idea was scrapped.
 * The Crater Edge was originally called The Void and the Dead Zone.
 * The Crater Edge is the deepest biome in the game.
 * The Crater Edge is one of the two biomes that do not harbor flora, the other being the Lava Lakes.
 * Being above the sea level will not stop Ghost Leviathans from spawning.
 * Being in a base will not either.
 * The further you go in the Crater Edge (horizontally or vertically), the more your character model and the screen will shake.[3]