Subnautica Wiki
Spoiler (BZ) Read at own risk

This article contains unmarked spoilers. Players new to the game would want to avoid or be cautious toward this article.


Detecting alien materials and a massive local energy mass in the 1,000 megawatt range.

― PDA, Dialogue


The Alien Thermal Plant is the smallest of the four main Alien Bases. It can be found in the Inactive Lava Zone, within the Lava Castle. It was built around one thousand years ago.

The generator is the source of power for all of the Alien technology on Planet 4546B.

There are two locked doors inside the Alien Thermal Plant, both of which require a Purple Tablet to unlock. Behind the first door is a blue Alien Tablet, which is used to access the Primary Containment Facility. Behind another door is the main generator for the facility, along with three data terminals, one of which unlocks the Blueprints for the Ion Battery and Ion Power Cell. There is also an Ion Cube Pyramid located inside. Inside another room is a Principal Alien Arch, linking back to the Quarantine Enforcement Platform.

Alien Robots roam inside the base, acting as a hazard for the player.

Data Bank Entry[]

This system is directly converting local thermal energy into electric current at 90% efficiency. Most of this energy is being stored in the battery-like devices within the plant itself, each of which holds enough to power a small city for a year. Some of it, however, is being drained off, presumably as it is distributed to other facilities on the planet.

The power plant appears to be fully automated and - given current understanding of the mechanisms involved - uninterruptible.

Fossil data recorded from the volcanic rock that was excavated to construct the alien power facility. It has been possible to extrapolate a number of key trends.

Genetic Divergence:
The aliens recorded data on indigenous organic remains originating between 10,000 and 1,000 years ago. The lifeforms on record feature an unusually low overlap with those encountered so far on 4546B.

Extinction Event:
Soil samples from 1,000 years ago contain 300% higher concentrations of organic remains than the soil average. Data supports a mass extinction event killing off a majority of species and forcing rapid adaptation amongst many of the survivors.

A power router in the thermal plant is distributing energy collected onsite to other facilities on the planet.

Primary Containment Facility Location Updated:
- Constructed within a natural chasm
- Connected to this cave network
- South south-east
- Area of volcanic activity
- Depth 1.4km

Power Distribution:
- Self-Warping Quarantine Enforcement Units - 5%
- Arch Network - 10%
- Sanctuaries (Alpha, Beta, Cappa) - 10%
- Quarantine Enforcement Platform - 35%
- Disease Research Facility - OFFLINE
- Primary Containment Facility - 20%
- Reserve - 20%

There is no clear way to interrupt the power flow.

It has been possible to extract useful information regarding alien ion power.

Ion cubes are grown artificially from a mineral substance, and are treated to remain in a stable state despite the huge ionic energy contained within. By installing an ion cube in an appropriate device this energy can be released as electrical power.

Using this knowledge it has been possible to synthesize new battery and power cell blueprints which leverage advanced ionic energy to last considerably longer.


Main article: Achievements
Spoiler alert: The following section contains story related material.
ATPAchievement Thermal Activity

Find the Thermal Plant

How to obtain: The player must discover the Alien Thermal Plant inside the Lava Castle.