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.

The edges of the playable area, the Crater, stretch downwards to a depth of 3,000 meters. At that point, the world cuts off on most ends, though some stretch out for a bit longer before dropping off. The bottom side of the Crater can be found here, which is a flat area that covers about 2km x 2km.

At a depth of 8,200 meters, the player reaches the farthest reachable point of the Crater Edge. At this point, the player will be teleported back to their lifepod.

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.

Bugs

 * When swimming very far out from the playable area, the player's screen will appear to shake violently. This is likely caused by floating point errors, meaning that the game is unable to accurately calculate the player's location.