Crater Edge

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

Adult Ghost Leviathans live in the Crater Edge, where they deter players from straying outside of the playable area. When entering the Crater Edge, a single Ghost Leviathan spawns in at first. If the player stays in the Crater Edge for 30 seconds, a second Ghost Leviathan will spawn. Staying in the area for another 30 seconds will spawn a third and final Ghost Leviathan. They will pursue the player until they return to the playable area, upon which all Ghost Leviathans retreat.

The Crater Edge is thought to be the old home of the ‘Gargantuan Leviathan’, which skull of a juvenile can be found in the Lost River.

Description
The Crater Edge is a large open ocean devoid of any flora, coral, and all but one non-microscopic fauna species: the three adult Ghost Leviathans that spawn when the player enters the biome.

The edges of the playable area, the Crater, stretch downwards to a depth of 1120 meters. At that point, the world cuts off on most ends. Underneath the Inactive Lava Zone and Lava Lakes, the map stretches farther to 1920 meters.

Once the player has gone 8,192 meters in any direction, the player reaches the farthest reachable point of the Crater Edge. Beyond this point, the player, as well as any piloted vehicle, will be teleported back to a randomly chosen location that is 10 meters above sea level and up to 250 meters away from the center of the map.

At approximately 4000 horizontal meters away from the map center, the zone ends. The Adult Ghost Leviathans cease spawning and retreat due the void biome "ending" according to the game and there is only an empty ocean, acting as the real end of the game's limit.

Fauna=
 * Ghost Leviathan

Trivia

 * The PDA refers to the Crater Edge as an “ecological dead zone” though this is an incorrect description of the area, as it supports enough planktonic life to sustain many huge filter feeders. Oceanic dead zones in real life refer to areas of hypoxic water unable to sustain life, whilst the Crater Edge supports a very large amount of life, despite having little diversity.
 * Before the Big Little Update, the Crater Edge used to have more realistic terrain at around 3000 meters depth, giving an appearance similar to real world abyssal plains. The bottom of the Crater was found here, which was a relatively flat area that covered a 4km x 4km square. At 3040 meters depth, the world completely cut off and all terrain would cease. It is unknown why this terrain was removed.
 * Sea Dragon Leviathans, Reaper Leviathans, and Crabsquids 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.
 * Subnautica: Below Zero has a similar biome found on Sector Zero known as the World Edge.
 * The Crater Edge's terrain goes beyond 8192 meters, however this cannot be viewed without bugs or mods.

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.
 * PS undefined Only on consoles, the game crashes upon reaching 3000 meters in depth. The reason is unknown. This doesn't happen very often anymore, though.
 * If the player is above the water upon passing 8196 meters in any direction, they will be stopped to a standstill and will begin to fall down at incredibly slow speeds and ultimately teleported back to the playable area upon reaching the water.
 * This also happens when the vertical 8196 meter barrier is crossed.