The massive size of the Abyss creatures is likely a reference to a real-world phenomenon called 'deep-sea gigantism', where species found in the deepest parts of the ocean are inexplicably far larger than their shallow water cousins.

It is never explained how the titanic creatures of the Abyss find food, as in regular gameplay, no creatures will naturally venture into the Abyss.

In 0.16.6.1 (Rising Tides), the ability to find alien materials on Abyss islands was added.

As of 0.11.0.7 (Uncharted Depths), there is no longer a general average abyssal depth, as the mission starting depth varies from level to level and only goes further down as submarines progress through the campaign.

In previous versions, The Abyss had a relatively fixed starting depth of ~1600m depending on level size and continued all the way to the bottom of each level.

Sandbox, PvP, and Mission Spawn Chances Difficulty Letters in single quotes (' ') denote subtypes which share level generation parameters but have different spawn lists. The specific chances and times can be found in the tables below difficulty ranges are both inclusive. The exact creature chosen and the time before another can spawn when it is killed depends on the difficulty and biome of the level, with the campaign having a different set of spawns compared to other game modes. Whichever creature is chosen by the game to defend the Abyss, it will only spawn once the player has actually entered it, not while they are traversing the level. The exception to this rule is during a hunting grounds mission the beast will never respawn when killed, creating a prime opportunity to mine the islands for resources. This can either give a crew respite to escape the Abyss or the time needed to extract the minerals found in its depths. Fortunately, once an Abyss creature is slain, there is a 'grace period' before another can take its place.

Anyone foolish enough to go outside during an encounter will be instantly killed by the bites of these titans. Additionally, they are capable of throwing the submarine around, potentially sending it crashing into walls to sustain more damage, or deeper into the ocean where the pressure will crush it. When attacking the hull, they do hundreds of structure damage per attack, quickly breaching and sinking the submarine. However, the danger posed by these titans more than makes up for the absence of other predators that would attack the submarine. As a result, normal monsters will never be encountered while traversing the Abyss. The Abyss is devoid of fauna save for three species, those being the Endworm, the Charybdis, and the Latcher. It should be noted that caves do not increase the amount or quality of the resources on a given Abyss island. Depending on the difficulty score of the level, the amount of resources on each island will vary, with higher difficulties granting greater rewards, and vice versa. These islands contain minerals that are otherwise hard to find within the biome, which can include coveted alien materials. In every level, 4 or 5 islands will spawn in the Abyss, with each island having a 50% chance to contain a cave of a type normally found within the biome the level takes place in. The hole next to the end outpost is guaranteed to spawn in every level, but depending on the biome, there may be more or fewer gaps in the floor that lead to the Abyss.

It is accessible through 'holes' in the passage walls, either in the floor or next to the outpost at the end of the level. The Abyss is the area beneath the main route of a level, often extending well below crush depth.

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