Subnautica Below Zero: How to Upgrade the Oxygen Tank and Breathe For Longer

Oxygen, or lack thereof, is a constant threat in Subnautica Below Zero, as you have to always return to the surface or a vehicle to avoid drowning. The best solution is to upgrade your scuba equipment for a larger oxygen supply, so we’ll show you how to upgrade your oxygen tank and breathe longer in our guide here.

Read More: How to Get the Seatruck

How to Upgrade the Oxygen Tank in Subnautica Below Zero

You can get an oxygen tank very early on in Subnautica Below Zero, but it’s not great and will need upgrading. To do that, you need to find the blueprints for the High Capacity O2 Tank and use those to craft it at a Fabricator. We’ll cover how to find the blueprints first.

High Capacity O2 Tank Blueprints Location

The High Capacity Tank actually isn’t that far away from the Drop Pod spawning location, found within the Twisty Bridges biome and not too deep from the surface level. The official coordinates for PC players are: 253, -124, -250, though that won’t help those on console.

To find it, you’ll probably want the Seaglide and standard oxygen tank at least, as it’s 120 meters down. However, for an easy means to find it, try the following:

  • From your Drop Pod, head North (ideally when it’s day and clear weather).
  • Go to the wall of ice that cuts you off about 100 meters North, and look for the massive overhanging formation with numerous long icicles hanging off it, like one half of a bridge reaching out over the sea. It’ll probably be to the East, depending on your location, but it’s not guaranteed.
  • Go directly beneath this outcrop.
  • From there, head South-by-Southwest for 350 meters until you’re well into the Twisty Bridges biome. Place a beacon or use existing ones to be certain of how far you’ve gone, or use the distance to the Emergency Supply Cache as a reference point. You should be roughly 460 meters away with it to the Northwest.
  • When in place, look down to see an especially deep area with numerous bridges overlapping it. You should be able to see a small rounded habitat tunnel on the Southwest side of this deep pit. That’s a marker for the area you’re heading to.
  • Go down with the Seaglide, avoiding the Brute Sharks, and interact with the databox next to it to get the tank blueprints!
Subnautica Below Zero tank upgrade
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The High Capacity Tank blueprints are in this little alcove, though the Brute Sharks can prove tricky.

How to Craft the Upgraded High Capacity O2 Tank

Now you have the blueprints, you can craft the High Capacity O2 Tank at the Fabricator with the following materials, none of which are particularly hard to get.

  • Standard O2 Tank (1)
  • Glass (2)
  • Titanium (4)
  • Silver (1)

The new tank will be automatically equipped, and will increase your maximum oxygen to 90. However, it also slightly slows down your speed when running or swimming, though not enough to be a real penalty.

How to Upgrade the High Capacity O2 Tank

Even from there, players can upgrade their tank further. By installing a Modification Station with the Habitat Builder, players can use Lithium to massively increase the tank’s capacity to 180, or give it a feature with a Wiring Kit wherein players can burn oxygen for a temporary speed boost.

You should also go find the Rebreather, which isn’t far from you and also helps survive at greater depths while you’re at it. Or head to our special guide on where to find Gold!

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