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Subnautica 2 guide intermediate

Subnautica 2 — Underwater Base Building: Site Selection, Power, Layout

A complete base-building playbook: where to put your first base, how to plan power (solar vs bio vs thermal), which functional rooms to add in which order, and the rules for deep-water pressure hulls.

· 13 min read · Updated Jul 20

Tested against: Subnautica 2 early-access build available at the time of writing. Module costs, base hull ratings, and power output values described here reflect the EA build’s behaviour as understood from public dev updates and the studio’s early-access patch notes. EA values may shift between patches — verify against the in-game habitat builder before relying on specific numbers.

Your base is your home, your staging ground, your vehicle dock, and your gene-farming hub. A well-planned base cuts your average expedition time in half; a badly-planned base costs you hours of swimming every session.

This guide covers the three things that actually determine whether a base is good or bad: site selection, power, and layout. The rest — decorations, room shapes, naming the fabricator — is personal preference.

The three things that make or break a base

  1. Site selection — wrong site means extra swimming every time you go anywhere.
  2. Power — wrong power means your base dies at night, and a dead base is uninhabitable.
  3. Layout — wrong layout means you bump into walls and can’t find anything.

Each section below is the in-game decision you make, in order. By the end you should be able to confidently place a base in any biome.

Site selection

The single biggest mistake new players make is placing their first base on the lifepod. The lifepod has oxygen and a bed, but it’s exposed, it has no room to expand, and it’s far from the materials you’ll need at mid-game.

Site criteria (in priority order)

  1. Safe depth — between 30 m and 80 m is the sweet spot for a starter base. Shallow enough that you can swim up quickly in an emergency; deep enough that leviathans don’t routinely patrol.
  2. Solar exposure — your starter base runs on solar. Place it where the seabed is flat enough to drop 3+ solar panels in a row, and where nothing overhead blocks sunlight.
  3. Material proximity — close to a silver cave cluster (for mid-game), close to Angelicas (for re-running gene unlocks), and reasonably close to a mid-depth wreck (for the moon pool blueprint).
  4. Leviathan-free — check for patrol paths. If you can hear leviathan roars at your proposed site, it’s the wrong site.
  5. Defensible terrain — natural walls (coral cliffs, rock ridges) help break line of sight. A base wedged into a cliff face is harder for leviathans to accidentally crash into.

200 m north of the lifepod, on the flat seabed between the Angelicas plant and the silver cave network. This location hits all five criteria and has room for a 12-room base plus a moon pool.

Site mistakes to avoid

  • Don’t build directly on top of a thermal vent — the heat damages your hull over time. Build 10–20 m away.
  • Don’t build inside a leviathan patrol tunnel — they’ll routinely pass through.
  • Don’t build where the terrain has a 30° slope — corridors won’t align cleanly to the seabed.

Co-op tip: in a 4-player squad, designate one player the base planner. They scout sites, place the initial corridor, and handle the moon pool. Everyone else explores.

Power

A base without power is a base that kills its inhabitants at night. EA has three power sources.

Solar panels (early game)

  • Output: depends on depth (light penetration) and time of day.
  • Best depth: 0–80 m.
  • Build cost per panel: low (basic metal + glass).
  • Limitation: zero output at night. You need backup batteries or another power source.

Bio-reactors (mid game)

  • Output: constant, low wattage.
  • Fuel: biological samples (small fauna, plant matter).
  • Best for: supplementing solar to keep lights on overnight.
  • Limitation: low output. Cannot run a moon pool + scanner station + fabricator simultaneously.

Thermal reactors (late game)

  • Output: high, constant.
  • Fuel: none — runs on ambient heat from a thermal vent.
  • Best for: late-game bases in the thermal vent biome (band 4).
  • Limitation: must be placed near an active vent. Cannot be built in shallow biomes.

The staged power plan

  • Starter base (stage 1): 3× solar panels + 2× backup batteries. This keeps you alive through the night.
  • Mid-game base (stage 2): add 1× bio-reactor. Now you have overnight power with redundancy.
  • Late-game base (stage 3): 1× thermal reactor (if built in vent biomes). Solar panels become decorative backups.
  • End-game base (stage 4): 2× thermal reactors, no solar panels. Permanent power.

Power mistakes to avoid

  • Don’t skip backup batteries. A single power outage is a squad wipe.
  • Don’t power everything from one source. Always have at least 2 power generators.
  • Don’t put solar panels on the roof. Place them on the seabed next to the base, in a flat row.

Layout

The default new-player mistake is to place a single square room with everything inside. That works for 30 minutes, then breaks down. Here’s a better starter layout.

The 12-room starter base

A balanced starter base, in build order:

  1. Corridor (entry) — at least 1 corridor between the outside and the first room.
  2. L-shaped lockable hatch — for security against leviathan breaches (in case the game adds breaching in future updates).
  3. Square room (1) — fabricator + storage locker + first-aid kit fabricator.
  4. Square room (2) — moon pool.
  5. Square room (3) — vehicle charging dock (extends moon pool).
  6. Corridor — splits the base into “exploration wing” (moon pool + scanner) and “domestic wing” (fabricator + bed).
  7. Square room (4) — scanner station + biology sampler storage.
  8. Square room (5) — bed + lockers.
  9. Square room (6) — water filtration unit + small plant farm.
  10. T-junction — vertical access shaft for future expansion.
  11. Vertical connector — to a second-floor observation dome.
  12. Glass observation dome — looks pretty, doubles as a decompression chamber.

Layout principles

  • Wet / dry split: separate “wet” rooms (moon pool, vehicle dock) from “dry” rooms (bed, fabricator). This keeps the dry rooms clean and reduces oxygen loss when entering.
  • Linear expansion: build outward from a central corridor. Don’t try to fit everything into a single mega-room.
  • Walkways, not ladders: corridors > vertical connectors when possible. Ladders are annoying to navigate.
  • Leave room for one more room: every base eventually needs one more room. Don’t paint yourself into a corner.

Functional rooms and what to put in them

RoomWhat goes insideWhy
Fabricator roomFabricator + storage lockersAll crafting, all material storage
Moon poolMoon pool itselfVehicle docking and recharging
Scanner roomScanner station + biology samplerBlueprint scanning + gene farming
Living quartersBed + personal lockers + waterSpawn point and water source
Power roomSolar panels + bio-reactorKeep power away from sleeping areas
Observation domeGlass walls, decorativeReduces cabin fever

Layout mistakes to avoid

  • Don’t place the moon pool and the bed in the same room — the moon pool is a wet, noisy, active space. Your bed should be in a quiet, separate area.
  • Don’t lock lockable hatches behind you — leave a corridor in / out so you can repair the base if something goes wrong.
  • Don’t build vertically without vertical connectors — ladder shafts are mandatory if you want a multi-floor base.

Pressure-rated bases (depth > 200 m)

If your base is below 200 m, you must use pressure-rated hulls. Standard corridors crack at depth.

When to upgrade

  • 200 m: hull starts taking strain. Switch to pressure-rated corridors immediately.
  • 800 m: standard corridors are guaranteed to fail.
  • 1,500 m: even pressure-rated corridors need reinforcement modules.

How to upgrade

You can’t “upgrade” an existing standard corridor. You have to:

  1. Build a pressure-rated corridor adjacent to it.
  2. Move your modules into the new corridor.
  3. Demolish the standard one.

Demolishing a corridor refunds materials. Plan your base layout before going deep.

Pressure mistakes to avoid

  • Don’t bring a standard corridor into a deep zone. It will crack.
  • Don’t place a thermal reactor in a non-vent biome. It won’t function.
  • Don’t ignore hull damage warnings. A cracked hull floods within minutes.

Common issues and fixes

”I built a base but I can’t find a moon pool location”

The moon pool is its own room type. It needs a 3×3 floor area with no obstacles above. If your base layout doesn’t have an open spot, build an L-corridor and place the moon pool there.

”My solar panels aren’t producing any power”

You’re either at night (solar produces nothing at night — wait until dawn), or you’re too deep (solar reaches max ~80 m), or your panels are placed under a rock overhang.

”My base is taking damage from leviathans”

This is rare in EA. If it happens, the leviathan is following you home — relocate the base 100 m in any direction. Don’t fight it on your home turf.

”I lost power and now my base is flooded”

Power outages cause hull breaches if your base has water inside. Always have at least 2 power generators. If you’re stuck, exit the base immediately and restore power from outside.

Frequently asked questions

Q: Can I move my base after building it? A: Only by demolishing and rebuilding. There is no “lift and shift” function. Choose your site carefully.

Q: How many rooms can a base have? A: In EA, the practical limit is around 30 rooms. Beyond that, render performance degrades noticeably.

Q: Do I need a base at every depth band? A: One base at a strategic mid-depth location is usually enough. A second base deep in the vent biome is useful for thermal reactor power. Beyond that, additional bases add material cost without much benefit.

Q: Does the base need to be sealed? A: Only if it’s pressure-rated. Standard corridors in shallow biomes don’t need sealing; they self-maintain internal atmosphere.

Next steps

EA content disclaimer

This guide describes Subnautica 2 in its early-access state as understood at the time of writing. Module costs, base hull ratings, and power output values change between EA patches. Always cross-check with the in-game habitat builder and the studio's official patch notes before relying on any specific number in this guide. Subnautica, the Subnautica logo, and all related marks are trademarks of Unknown Worlds Entertainment. This site is unofficial and unaffiliated.