Ways to Boost Your Oxygen Supply in Subnautica 2

Boosting your O2 capacity is one of the first priorities in Subnautica 2. Constantly resurfacing for air can be a hassle when you’re trying to get things done underwater. Your oxygen level is essentially the game’s progression system, dictating how deep you can dive and what rare resources you can access.

There are several ways to enhance your oxygen supply, so let’s break down the methods in the order you’ll find them useful.

Your initial solution for extended underwater breathing is the Oxygen Tunic. Contrary to what it sounds like, this isn’t a piece of gear but rather a blue, blob-like organism that releases oxygen bubbles into the water. Swim into these bubbles to replenish your O2 and refill your Air Bladders.

While exploring, you’ll also encounter small funnels blocked by Bloom Sap. Use your Survival Multitool to clear this away, and it will create a column of bubbles that you can hover in to gradually restore your oxygen.

Additionally, keep an eye out for air pockets in cave ceilings where you can dip in to refill your oxygen. These methods are particularly useful early in the game when your oxygen capacity is limited.

Once you can craft a basic battery using an Acidic Raion Pouch (and have made a scanner), head to the Welcome Center colony ruins located southeast of the Life Pod. Here, you can plug a battery into a wall outlet to access the Biolab, allowing you to equip Biomods (essentially skills) onto your character.

The Oxygen Control passive Biomod is incredibly beneficial, as it reduces your O2 consumption while stationary, making it ideal for scanning or investigating underwater.

These flotation tools are invaluable, and I recommend carrying several. You can craft one using:

To create rubber, combine two Lucifer Rotsacs in the ‘Resources’ section of the Fabricator.

Air Bladders are particularly useful because you can consume them to partially refill your oxygen or use them to quickly ascend to the surface when you’re running low on air. This versatility also helps you escape predators since you rise rapidly. Whenever you refill your oxygen, you’ll also replenish these handy items.

Your first significant oxygen upgrade comes in the form of the Standard Air Tank, which requires:

The silver can be a bit tricky to find, but there are spots near the Lifepod where you can easily collect it. Crafting this tank increases your overall O2 level, allowing you to stay underwater longer, so it’s a smart move to make it as soon as you can.

The next upgrade is the High Capacity Air Tank, which involves a bit more effort. You’ll need:

First, you must acquire the recipe data card for the High Capacity Air Tank, which can be found in a colony ruin in a deeper area southwest of the Life Pod. I recommend bringing Air Bladders and unlocking the Wavemaker for faster movement. The route is shown in a video, but generally, you’ll want to:

Make sure to scan the Processor while you’re there (you’ll need that soon), and grab the Room recipe data card for your base. You’ll also need to collect some lithium, which can be found on a table just outside the colony ruins mentioned earlier, resting in a piece of coral.

Once you have everything, return to craft the High Capacity Air Tank. First, build the Processor (its components are easy to gather), then switch the recipe to Plasteel Ingot and add:

Combine that with your Standard Air Tank at the Fabricator, and you’ll have your High Capacity Air Tank.

While the Rebreather doesn’t increase your oxygen capacity, it does reduce the O2 you consume when diving deep. You can find and scan one of these in the habitation built into the cliff face, just north of the colony ruins where you found the High Capacity Air Tank recipe. This area is all southwest of the Life Pod.

To craft the Rebreather, you’ll need:

You can create Fiber Mesh in the ‘Resources’ section of the Fabricator using two fibers and one Strong Acid, while the System Chip requires one Wiring Kit and two quartz. You should already have the Wiring Kit unlocked since it uses silver.

Though I haven’t fully unlocked this yet, the first scan location for a Portable Oxygen Generator is in The Great Jaw, near the colony ruins where you found the High Capacity Oxygen Tank recipe and the lithium. It resembles a giant pod-like mouth, so it’s hard to miss. Swim inside and scan the generator, but avoid triggering the purple strands unless you want it to close.

Vehicles are another excellent way to maintain oxygen, as you’ll refill your O2 whenever you enter one, provided it’s powered. You can build a Tadpole relatively early on, which is essential for quick and extensive exploration of the ocean.