Best Oxygen Tank Upgrades in Subnautica: Below Zero
The files hold four tanks, each built from the one before: Standard, High Capacity, Ultra High Capacity (the one that needs 4 Lithium and the Modification Station) and the Lightweight tank. The Ultra tank's 3 fragments have no fixed pin, so it is a random find. The files give no capacity numbers, only the descriptions.
- Tanks4each made from the last
- Ultra tank3 fragments0 fixed pins
- Ultra tank needs4 Lithiumat the Modification Station
- Other gear6booster, rebreather, fins, suits
"Best" is a ranking I can defend from the files: the tank ladder follows the recipes. I cannot rank by oxygen or depth, because those figures are not in what I read.
On this page
The tank ladder
The Standard tank is made from Titanium and Fiber mesh; every later tank takes the previous one as an ingredient.
| Tank | Crafted at | Ingredients | How it unlocks | What the game says |
|---|---|---|---|---|
 Standard O₂ Tank | Fabricator | 2 Titanium, 1 Fiber mesh | a scan or a starting goal | O₂ mix. Compressed, breathable air. |
 High Capacity O₂ Tank | Fabricator | 1 Standard O₂ Tank, 2 Glass, 4 Titanium, 1 Silver ore | data box: Shallow Twisty Bridges, 128 m below sea level | O₂ mix. Highly-compressed breathable air. |
 Ultra high capacity tank | Modification station | 1 High Capacity O₂ Tank, 4 Lithium | 3 fragments, 0 pinned (random spawns only) | Additional air capacity. |
 Lightweight high capacity tank | no station listed | 1 High Capacity O₂ Tank, 1 Plasteel ingot | not stated in the files | Lighter build allows for enhanced manoeuvrability. |
The Ultra High Capacity tank
Counted down to raw materials, the Ultra tank with the two tanks under it is 6 Titanium, 4 Lithium, 4 Quartz, 2 Creepvine sample, 1 Silver ore; the Ultra step itself adds the 4 Lithium. Its fragments are rolled per game, with none placed by hand, so the map cannot send you to one. Where Lithium is likeliest: the ore guide.
Other dive gear
The rest of the dive kit, with the unlock the files give. Where the files give none, the table says so.
| Item | Crafted at | Ingredients | How it unlocks | What the game says |
|---|---|---|---|---|
 Booster tank | Fabricator | 6 Titanium, 4 Quartz, 3 Silver ore, 2 Creepvine sample | 2 data boxes: Purple Vents, 139 m below sea level; Tree Spires, 453 m below sea level | Use oxygen to give a speed boost |
 Rebreather | Fabricator | 2 Creepvine sample, 2 Silver ore, 1 Creepvine seed cluster | data box: Shallow Twisty Bridges, 172 m below sea level | Conserves oxygen when diving deeper. Absorbs and recycles CO₂ into breathable air. |
 Ultra glide fins | no station listed | 2 Creepvine seed cluster, 1 Lithium, 1 Titanium | not stated in the files | Streamline construction enhances swim speed considerably by comparison to regular fins. |
 Swim charge fins | Modification station | 3 Young Cotton Anemone, 2 Silver ore, 1 Creepvine seed cluster, 1 Gold, 1 Salt deposit | data box: Lily Pads, 204 m below sea level | Wirelessly charges your held tool while you swim. |
 Reinforced dive suit | Fabricator | 2 Diamond, 2 Titanium, 1 Ruby, 1 Spiral Plant Clipping | 1 fragment, 1 fixed pin | Heavy synthetic fiber dive suit, providing physical protection and enhanced survival in extreme temperatures. |
 Water filtration suit | Fabricator | 2 Copper ore, 2 Ruby, 1 Gel sack, 1 Spiral Plant Clipping | data box: Purple Vents, 411 m below sea level | Reclaims moisture from the body and provides clean, drinkable water. |
What you start with
A story goal named UnlockBasicBlueprints unlocks 12 recipes: fins, survival knife, standard o₂ tank, flashlight, scanner, first aid kit, waterproof locker, fiber mesh, silicone rubber, battery, glass, copper wire. The standard tank is among the items that fire the next goal, which adds the repair tool, pipes, the wiring kit and the computer chip. The files do not say whether either goal runs at the start of a game.
Common mistakes
- Skipping the High Capacity tank. The Ultra tank is made from it.
- Hunting a map pin for the Ultra tank's fragments. There is none.
- Looking for a capacity number. The files hold none.
About these numbers
Every number here is read from the game files of the Steam build of 12 Aug 2025. Fixed pins and recipes are exact. Spawn chances come from a model of the game's spawner tables and have not been checked in a running game. Anything the files do not hold is marked on the page.
Areas in the unlock column are the map's own labels.
Pages to keep open
Related pages
Sources
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