Last updated: 13 July 2026

Subnautica 2 Base Building Guide — Habitats, Power & Hull Integrity

Building an underwater base in Subnautica 2 is one of the most satisfying parts of the game, and also one of the easiest ways to lose hours of progress if you ignore a few core principles. Hull integrity, power management, and module placement work together in a system that rewards planning. This guide explains how each piece fits together — from your very first tube module to a multi-room deep-sea outpost — so you build confidently rather than by trial and error.

01How the Habitat System Works

Every base in Subnautica 2 is assembled from modules using the Habitat Builder tool. Modules connect end-to-end or via I/L/T/X junction pieces and all share one unified air supply once connected. The two numbers you always need to watch:

• Hull Integrity: starts at a base value and decreases with every module, window, or hatch you add. If hull integrity reaches 0, the base floods — you lose all stored resources inside. It increases when you add reinforcement pieces.
• Power: all powered equipment (Fabricators, grow beds, lights, Scanner Rooms) draws from a shared grid. Run out of power and automated systems shut down, though the air supply continues as long as the base is sealed.

Think of hull integrity as a budget. A small base with no windows might sit comfortably at +10 integrity. Start adding large windows and extra rooms without reinforcing and that drops to -2 — at which point the base starts taking on water. Always reinforce before you expand.

Update 1.1 increased the maximum deconstruction size for bases, making it easier to dismantle larger sections of an existing base at once when redesigning your layout.

02Essential Early Modules

You do not need a large base to be effective. The following four-piece setup covers all early-game needs and maintains solid hull integrity:

• Corridor Tube (×1–2) — your main living space. Each tube costs minimal hull integrity. Connect them in a straight line to keep the footprint simple.
• Fabricator — place one inside your first tube. This is your crafting hub; you should never need to run back to the escape pod.
• Storage Locker (×2–4) — wall-mounted inside tubes. One for raw materials, one for food and equipment.
• Storage Cache — added in update 1.1; unlike the standard Storage Locker, items stored inside do not feed into nearby Fabricator recipes automatically. Use it for rare materials you want to keep out of automatic crafting.
• Medical Kit Fabricator — auto-produces a medical kit every 30 minutes. Always include one — free health recovery is invaluable.
• Power Cell Charger — recharges the batteries in your Seaglide, Flashlight, and scanner. Without this you'll constantly run out of power mid-dive.

Don't build a Scanner Room in your first base unless you're near a specific resource you need — it consumes significant power and is better placed in a second outpost close to deeper biomes.

03Hull Integrity: How to Manage It

Hull integrity is the make-or-break system for mid-game bases. Here's a practical breakdown:

• Base hull integrity value: determined by your deepest module. The deeper you build, the lower your starting integrity.
• What lowers it: rooms (−1 to −3 each), hatches (−1), windows (−2 to −4 depending on size), corridors (−1).
• What raises it: Hull Reinforcement pieces (+7), External Buttresses (+2), Reinforced Wall pieces (+1). These are cheap to craft once you have Plasteel Ingots.
• Recommended buffer: always keep hull integrity at +3 or above to account for future additions.

The most common mid-game mistake is building a large room (high hull integrity cost), adding a panoramic window to it (another −4), and suddenly sitting at negative integrity without noticing until the base floods. Before you add any decorative or large module, check the hull integrity preview shown by the Habitat Builder.

At deep-water outposts (below 200 metres), Plasteel Ingots (smelted from Titanium Ingots + Lithium) become essential for both reinforcements and the structures themselves — start farming Lithium from the Mushroom Forest before you try to build deep.

04Power: Solar, Thermal, and Bioreactors

A base with no power is a base where nothing automatic works. The three main early-to-mid power sources:

Solar Panels — placed on external flat surfaces, they produce power during daylight hours and trickle-charge power cells at night. Two solar panels are enough to run a small base continuously in shallow water. Solar stops working below roughly 200 metres where no sunlight penetrates.

Thermal Plant — generates constant power from geothermal vents found in volcanic biomes (typically 300+ metres deep). Build one near a vent and it produces power around the clock with no maintenance. This is the power source for any deep-sea outpost. Multiple plants can be connected via Power Transmitters to deliver energy back to distant modules.

Bioreactor — burns organic material (fish, plants, hatched eggs) to produce power. Less efficient than solar or thermal but useful as a backup or in biomes without vents. A Bioreactor loaded with a stack of Creepvine or spare fish will run a small base for a full in-game day.

• Always include at least one Power Cell Charger so your handheld tools never run flat on a long dive.
• Add a second Solar Panel before any other upgrade — the extra power bank covers overnight draw without issue.
• If your base flickers off at night, add a Thermal Plant or Bioreactor — two solar panels won't cover heavy overnight power draw.

05Best Early Base Locations

Location is the biggest decision that shapes your mid-game. Here's how to pick well:

Starting base (0–40 metres): Build within 200–300 metres of your escape pod in the shallow reef zone. This biome has abundant Titanium, Quartz, and Copper in limestone outcrops, steady sunlight for solar power, and relatively passive creatures. Depth is low enough that hull integrity is not a serious concern yet.

Second outpost (100–200 metres): Once you've explored the shallow biomes and need to go deeper, build a relay outpost at the edge of the Kelp Forest or the entrance to the first cave system. This cuts your swim time significantly on resource runs and gives you a safe oxygen source near deeper dives.

Deep outpost (300+ metres): Build near a thermal vent when you're ready to explore the volcanic and abyssal biomes. Keep this base minimal (Scanner Room + Storage + Fabricator) and power it with a Thermal Plant. Hull Reinforcements are mandatory at this depth.

• Avoid building inside narrow caves early on — hatches clip easily and base flooding is hard to notice in tight spaces.
• A flat sandy bottom is the easiest surface to build on without clipping issues.
• Building near a large wreck gives you scanner room synergy — wrecks are dense with resources.

06Useful Rooms for Mid and Late Game

Once your first base is stable, these modules are worth adding:

• Scanner Room — scans a radius around the base for resources and marks them on your HUD. Essential for efficient resource farming. Requires copper wiring and titanium.
• Tadpole Dock — docks and recharges your Tadpole vehicle. Build this before you craft a vehicle, not after. Update 1.1 reduced the dock's platform and rail footprint, making it easier to fit into smaller base rooms.
• Alien Containment — a water tank where you can breed fish for a permanent food supply. Two fish of the same species will eventually breed. Invaluable for long base stays.
• Large Room — high hull integrity cost (−3 to −5) but gives a lot of interior space. Use when you need a proper workshop or grow-bed room. Always reinforce before adding.
• Observatory — only for atmosphere and navigation reference; costs −4 hull integrity for no functional benefit. Build only once your base is well reinforced.