Subnautica: Below Zero: Complete Guide

A spoiler-light survival guide to Subnautica: Below Zero: first-hour priorities, how cold and survival stats work, vehicles and upgrades, base building, key biomes and creatures, a story progression outline, and PC notes after the 2025 patches.

Researched September 2026 — current as of the October 2025 security hotfix (Unity update; legacy and alternate Steam branches disabled) and the August 2025 patch. Live games change; check the linked sources if something differs.

Quick Start

• Pick your mode. Survival is the intended experience. Freedom removes hunger and thirst; Hardcore is permadeath; Creative is unlimited; Custom (added in the September 2022 "What the Dock" update) lets you tune damage, day length, creature aggression, diet, and more.
• Scan everything. The Scanner is how you learn blueprints. Scan fragments of vehicles and base pieces, and read PDAs for leads.
• Early crafts: Survival Knife, Scanner, a Repair Tool, and then a Seaglide for fast swimming. Oxygen tanks come next.
• Watch body heat on land. Temperature drops on land and faster in storms. Warm up near Thermal Lilies, heat sources, or indoors; a Cold Suit is essential for serious land exploration.
• Follow the signal markers and PDA leads. The story guides you with objectives; each new base or signal usually unlocks key blueprints.
• Build a small base early. A Fabricator, storage, a bed, and a power source are enough. Expand later.
• Get the Mobile Vehicle Bay to build the Seatruck and later the Prawn Suit. The Seatruck is your mobile base.
• Respect deep water. Vehicles have crush depths. Upgrade depth modules before diving deeper.
• Stuck? Use the Unstuck button in the pause menu (added in 2022) to get out of terrain.

Survival Systems

Stat | How to manage it

Oxygen | Surface, use air bubbles, or craft bigger O2 tanks. Vehicles and bases supply air

Health | First Aid Kits; avoid predators

Food | Cook fish and grow plants; fresh cooked fish spoils, so cure it for storage

Water | Filtered Water crafted from Bladderfish, Disinfected Water, or a water filtration setup in your base

Body heat | On land only: shelter, Thermal Lilies, heat sources, hot drinks, and the Cold Suit

Cold Suit: the full set (suit, helmet, gloves) dramatically slows heat loss. Build it before heading into snowy peaks.

Snowstorms: on land, storms drop your temperature and reduce visibility. Wait them out in shelter if you're low.

Tools and Gadgets

Tool | Use

Survival Knife | Harvest and defend

Scanner | Learn blueprints and creature data

Repair Tool | Fix vehicles and bases

Seaglide | Fast underwater travel; also shows a map

Flashlight | Dark caves

Propulsion Cannon | Move objects and throw things at predators

Air Bladder | Emergency lift to the surface

Beacon | Mark locations

Pathfinder Tool | Drop a trail back out of caves

Thumper | Distracts creatures on land

Spy Pengling | Scout small tunnels remotely

Vehicles

Vehicle | Where | Notes

Seaglide | Crafted | Fast early travel

Seatruck | Mobile Vehicle Bay | Modular vehicle that tows modules; your main travel base

Prawn Suit | Mobile Vehicle Bay | Walking exosuit with grappling arm and drill arm for mining large resource deposits

Snowfox | Built after finding its blueprint | Land hoverbike for snowy regions; recharges on a Hoverpad

Seatruck modules

• Storage Module: extra lockers.
• Fabricator Module: craft on the go.
• Sleeper Module: bed and storage.
• Aquarium Module: catches fish automatically.
• Docking Module: carries a Prawn Suit.
• Teleportation Module: teleport-based travel between your Seatruck and your base (read its in-game description for the exact rules).

Seatruck Dock: since the What the Dock update, a base piece docks the Seatruck plus modules at your base.

Depth: each vehicle has a crush depth that you can extend with depth upgrades crafted at the Modification Station or Vehicle Upgrade Console. Warnings appear before damage; never ignore them.

Snowfox notes (2025 patch)

The August 2025 patch made the Snowfox much less frustrating:

• Terrain impact damage cut to 12% of what it was.
• Less likely to get stuck on obstacles.
• Deploys facing your direction.
• Ice Worm encounters knock you off only 25% of the time (down from 100%), and the worm no longer damages you from any distance.

Base Building

• Habitat Builder places base pieces. Scan fragments to unlock more.
• Power: start with solar panels in shallows. Thermal plants work near hot vents. Batteries and power cells store energy.
• Must-haves: Fabricator, Modification Station, storage lockers, bed, a water source, a food source (planters or aquarium), and a Scanner Room.
• Scanner Room: scans for resources in range. Use it to find rare materials instead of searching blind.
• Location: somewhere central with shallow access, a stable heat or light source, and room to dock the Seatruck.
• Land bases are easier than they look: any compartment above water keeps you warm even without power, solar panels stay effective outdoors (even in storms), and there's no hull integrity to worry about. You need the Habitat Builder, foundations, a compartment, a door, and stairs to reach hatches on land. The Delta Island area and the shallow Twisty Bridges are popular spots.

Biomes and Resources

Key biomes include Arctic Kelp Forest, Twisty Bridges, Purple Vents, Thermal Spires, Lilypad Islands, Tree Spires, Crystal Caves, Glacial Basin, and Glacial Bay, plus deeper cave systems.

Resource | Where to start looking | Used for

Titanium / Copper / Quartz | Shallow outcrops and scrap | Early tools and base pieces

Silver / Gold | Sandstone outcrops | Electronics

Ruby | Deeper vent and cave biomes; scan for it with the Scanner Room | Advanced vehicle parts

Kyanite | Small blue crystals among the crystal clusters in the Crystal Caves (below about 500 m) and in the Fabricator Caverns | Seatruck Depth Module Mk3 and Prawn Suit Depth Module Mk2; you need it to finish the story

Large resource deposits | Found with the Scanner Room; mined with the Prawn Suit drill arm | Bulk materials

Tip: if you can't find a resource, craft a Scanner Room and search for it. It's faster than guessing.

Kyanite run checklist

Kyanite sits near 500 to 600 m, so treat it as an expedition:

• Seatruck: at least the Depth Module Mk2 (Mk3 is better once you've crafted it), plus the Perimeter Defense and Afterburner upgrades.
• Suit: a Rebreather and a High Capacity O2 Tank.
• Route: hug the edges of the Crystal Caves. A Shadow Leviathan patrols the middle.

Oxygen at a glance

Source | Oxygen

Base suit | 45 units

Standard O2 Tank | +30 (75 total)

High Capacity O2 Tank | +90 (135 total)

Ultra High Capacity O2 Tank | +180 (225 total)

Oxygen Plant bulb (caves) | 30 units

Raw Bladderfish (eaten) | 15 units

Frozen air bubbles | Cut open with the Laser Cutter for three bubbles

The Rebreather slows oxygen use below 100 m.

Creatures and Threats

Creature | Threat

Brute Shark | Aggressive; keep moving

Squidshark | Aggressive but manageable; can harass vehicles

Chelicerate | Aggressive leviathan in the East Arctic, Purple Vents, and Tree Spires; avoid or distract

Void Chelicerate | Guards the edge of the map (World's Edge); turn back

Shadow Leviathan | Aggressive leviathan in the Crystal Caves and Fabricator Caverns; avoid its territory

Glow Whale | Peaceful leviathan around the East Arctic and Lilypad Islands

Ventgarden | Peaceful floating leviathan in the Tree Spires

Snow Stalker | Land predator in snowy areas

Ice Worm | Burrowing land threat in the snowy Arctic Spires region; bursts from the ground

Cryptosuchus | Aggressive reptile-like creature found in some caves; keep your distance

Lily Paddler | Hypnotizes you and pulls you toward it

Sea Monkey | Steals your tools

Pengwing | Friendly; the Spy Pengling is based on them

Titan Holefish | Huge, peaceful; you can swim through it

Distractions: throw or release fish to distract predators, use flares, and use the Propulsion Cannon or Thumper as tools.

Story Progression Outline (Light Spoilers)

You play Robin Ayou, who comes to planet 4546B to investigate the death of her sister Sam.

• Arrival and early leads: find Sam's traces and Alterra facilities. Early bases like Outpost Zero provide key logs.
• Meet Al-An: a digitized Architect consciousness found at an alien site, which downloads itself into Robin's mind. Robin agrees to help build a new body for it.
• Alterra research stations: Delta Station, the Phi Robotics Center, and others reveal what Sam uncovered and unlock important blueprints.
• Marguerit Maida: a survivor from the Degasi expedition (from the first game) who helped Sam.
• Architect components: Al-An sends you to alien sites to collect the parts for its new body.
• The finale: learn that Sam sabotaged Alterra's research on the Kharaa bacterium and the Frozen Leviathan (at the Phi Excavation Site), recover her cure, then complete Al-An's body and leave through an Architect phasegate.

The story is much more guided than the original Subnautica. If you're lost, re-read your PDA's latest log.

Common Mistakes to Avoid

• Heading onto land without a Cold Suit.
• Ignoring crush-depth warnings.
• Leaving the Seatruck in open water where predators can reach it; park near base or dock it.
• Not building a Scanner Room, then searching for resources blindly.
• Carrying too little oxygen in caves; use a Pathfinder trail.
• Letting Sea Monkeys steal tools.
• Forgetting batteries and power cells for vehicles.

Advanced Tips

• Seatruck as a mobile base: Fabricator, Sleeper, and Storage modules let you do long expeditions without returning home.
• Prawn Suit + Docking Module combos for deep mining.
• Scanner Room HUD chip shows resources on your screen while exploring.
• Aquarium Module is a free food source.
• Console commands (PC): open the console with Shift+Enter since 2021. Useful for fixing bugs; commands can disable achievements.
• Custom mode lets you create your own challenge, such as peaceful creatures with harder survival.

PC Notes

• October 2025 security hotfix: Unknown Worlds updated Unity after a Unity-reported vulnerability and disabled all legacy and alternate Steam branches. Mods on legacy branches must be removed or updated for the current version to preserve saves.
• Steam Cloud saves were restored in 2022.
• Mobile versions launched on 26 February 2026; the PC game is unchanged.
• Subnautica 2 is the studio's next game (Unreal Engine 5, optional co-op for up to four players), launching in Early Access.

FAQ

Do I need to play Subnautica first? No, but the story connects to it. Playing the original first gives more context.

How long is Below Zero? About 20 hours for the main story, around 26 to 27 hours with some exploration, and roughly 32 hours for 100%.

Is there multiplayer? No. Below Zero is single-player.

How do I stay warm? Use the Cold Suit, shelter, heat sources, and Thermal Lilies.

Where do I build the Seatruck? At the Mobile Vehicle Bay after finding its blueprint.

Can I use mods after the 2025 hotfix? Only if they're updated for the current version.

Is Below Zero on sale often? It regularly goes on sale; it was 75% off in April 2026.

Sources

• Steam — Subnautica: Below Zero store page and announcements
• Steam — Below Zero Security Hotfix (October 2025)
• Steam — Below Zero 2025 Patch (August 2025)
• Wikipedia — Subnautica: Below Zero
• TheGamer — Where to find Kyanite
• TheGamer — Every Leviathan and where to find them
• TheGamer — How to get oxygen
• TheGamer — How to build a base on land
• TheGamer — How long to beat