How to Get to the Primary Containment Facility in Subnautica — Full Route

The Primary Containment Facility is the final story location in Subnautica: a Precursor prison built ~1,000 years ago inside the Lava Lakes, home to the last Sea Emperor Leviathan and her five eggs. Getting there is a three-stage expedition — the Lost River, the Inactive Lava Zone, then the Lava Lakes — gated by the depth module chain (Cyclops or Prawn MK3, 1,700 m) and the Blue Tablet from the Alien Thermal Plant. This guide covers the exact route with coordinates, the equipment checklist, where every required item lives, and the Hatching Enzymes sequence that finishes the game's story — including the Sea Crown, the rarest flora you'll ever need.

Here's what you'll learn:

• The exact route: Lost River → Inactive Lava Zone → Lava Lakes
• The depth module chain and what you must craft before diving
• Where the Blue Tablet and Purple Tablets come from
• The Alien Thermal Plant's role and what's inside it
• Every Hatching Enzymes ingredient and where the arches take you
• Where to find the Sea Crown and how to farm it

Official resources: Steam store page · Official Subnautica Wiki — Primary Containment Facility · Official Subnautica Wiki — Alien Thermal Plant · Official Subnautica Wiki — Hatching Enzymes · IGN Subnautica page

The Route at a Glance

The facility sits at coordinates 200 -1440 -222 in the Lava Lakes, reachable through two entrance tunnels. The full journey, bottom to top:

1. Lost River — enter from the Blood Kelp Zone or Bulb Zone; collect nickel for the MK2 depth module.
2. Inactive Lava Zone — enter through the Lost River's lava falls; visit the Lava Castle and the Alien Thermal Plant for the Blue Tablet; collect kyanite for the MK3 module.
3. Lava Lakes — through the tunnels at -300 -1270 -150 (southeast) or 90 -1240 360 (north of the Lava Castle); the facility's exterior is here.
4. Inside — Blue Tablet on the entrance forcefield, then a second Blue Tablet for the Moonpool room, then the Aquarium and the Sea Emperor.

Per the official Subnautica Wiki: "There are two entrances to the Lava Lakes containing the Primary Containment Facility; co-ordinates are -300 -1270 -150 and 90 -1240 360, southeast, and directly north of the Lava Castle, respectively."

The Equipment Checklist (Non-Negotiable)

The depth module chain: Cyclops MK1 (900 m, Plasteel + 3 Ruby) → MK2 (1,300 m, needs Nickel Ore from the Lost River) → MK3 (1,700 m, needs Kyanite from the Inactive Lava Zone). The Prawn Suit chain is identical. This is the loop that forces you through the Lost River before the lava zones — the full Cyclops upgrade mechanics are in our Cyclops guide, and the biome depths are mapped in our biome map guide.

Where the Blue Tablet Comes From (and the Purple Tablets)

• Purple Tablet (needed to open the Alien Thermal Plant's doors): crafted from 1 Ion Cube + 2 Diamond at the Fabricator. Its blueprint/fragments are found at the Floating Island Degasi Base, Mountain Island, the Mountains Caves and the Quarantine Enforcement Platform. The diamonds are the pain point — the farms are in our diamond guide.
• Blue Tablet: found inside the Alien Thermal Plant, behind the first Purple Tablet door. You need two total — one to open the facility's entrance forcefield, a second for the Moonpool room inside.

The Alien Thermal Plant (Stop Before the Facility)

The Alien Thermal Plant sits inside the Lava Castle in the Inactive Lava Zone (coordinates -75 -1182 5). It's the power plant for all Precursor tech on the planet, and it's worth the detour for four things:

1. The Blue Tablet (behind a Purple Tablet door).
2. The Ion Battery and Ion Power Cell blueprints (one of the data terminals) — 6,000-energy Cyclops bank, discussed in our Cyclops guide.
3. The Ion Cube pyramid — a renewable Ion Cube source (the pillar re-fabricates a deposit every ~2 minutes).
4. A Principal Alien Arch linking back to the Quarantine Enforcement Platform — your escape hatch after the story.

Watch for the roaming Alien Robots inside — they damage you on contact.

Inside the Facility: From Entrance to Aquarium

The facility has three sections (per the official wiki):

1. Antechamber — the octagonal hall with the Ion Cube Fabricator pillar in the center, specimen cases, and six doorways. The Egg Laboratory (43 eggs, including a Sea Emperor egg and two Sea Dragon eggs) and the Dissection Lab are off this room. The Moonpool room's forcefield needs your first Blue Tablet.
2. Moonpool Room — opens with the second Blue Tablet; the corridor beyond leads to the Aquarium.
3. Aquarium — a huge flooded chamber where the Sea Emperor Leviathan lives, with the Incubator Device holding the five eggs. This is where the ending happens.

The Hatching Enzymes (How to Finish the Story)

After talking to the Sea Emperor, activate the Aquarium Arch — this unlocks the Hatching Enzymes blueprint and the four Alien Arches that teleport you to the ingredients:

Craft 1 Hatching Enzymes at the Fabricator (one of each ingredient), insert it into the Incubator Device — one enzyme hatches all five eggs. The hatchlings provide Enzyme 42, which cures the Kharaa infection, and the Aquarium Arch opens to the Quarantine Enforcement Platform for the final cutscene. The achievement "Optimal Health" pops after the healing sequence.

Sea Leviathans You'll Meet on the Way

The lava zones are Sea Dragon territory (3 total: two in the Inactive Lava Zone, one in the Lava Lakes), and the Lost River has Ghost Leviathan juveniles plus the adult in the Northern Blood Kelp entrance. None of them need to be fought — the engine-off/slow-speed discipline from our Cyclops guide and the full threat breakdown in our leviathans guide are exactly what you want before this run.

FAQ

How do I get to the Primary Containment Facility in Subnautica?

Lost River → Inactive Lava Zone → Lava Lakes (entrances at -300 -1270 -150 and 90 -1240 360). Bring a Cyclops or Prawn with the MK3 depth module, two Blue Tablets, and thermal or spare-cell power.

Where do I find the Blue Tablet?

Inside the Alien Thermal Plant in the Lava Castle (Inactive Lava Zone, -75 -1182 5), behind a Purple Tablet door. You need two total — one for the facility entrance, one for the Moonpool room.

What depth modules do I need to reach the Primary Containment Facility?

The MK3 (1,700 m) on the Cyclops or Prawn Suit. The chain is MK1 (900 m, Plasteel + Ruby) → MK2 (1,300 m, Nickel from the Lost River) → MK3 (Kyanite from the Inactive Lava Zone). The Seamoth caps at 900 m and cannot make the trip.

Where do I find the Sea Crown?

Bulb Zone, Dunes Sinkhole, Jellyshroom Caves entrance, Grassy Plateaus caves, and the Sea Emperor's aquarium. Three knife slashes give 5 seeds; plant them in an Exterior Growbed (~11:40 to mature).

How do I craft the Hatching Enzymes?

Activate the Aquarium Arch, then use the four Alien Arches to collect Ghost Weed (Lost River), Eye Stalk (Crag Field), Fungal Sample (Mushroom Forest) and Bulb Bush (Bulb Zone), plus a Sea Crown from the aquarium. Craft 1 Hatching Enzymes at a Fabricator and insert it into the Incubator — it hatches all five eggs.

Related Guides

• Subnautica Leviathans Guide — All Types and Locations
• Subnautica Biome Map — Every Biome and Depth Range
• Subnautica Cyclops Guide — Fragments, Upgrades and Pilot Tips
• Subnautica Diamond Guide — Where to Find It and Every Recipe
• Subnautica Alien Containment Guide — Breeding and Hatching

Last updated: August 13, 2026.