The Portable Oxygen Generator is a hand-carried utility device in Subnautica 2 that produces breathable air through electrolysis while it has battery power. It sits between the consumable Air Bladder and the permanent Air Tank upgrades, giving you a refillable oxygen source you can take into deeper dives.
Quick answer: Scan the Portable Oxygen Generator fragments inside a Great Jaw, then build it with the Habitat Builder using 3 Titanium and 2 Lithium. Load a Basic Battery to make it work.
Where to find the Portable Oxygen Generator blueprint
The blueprint comes from scanning fragments tucked inside a Great Jaw, the large fleshy purple-and-green organism that doubles as one of the more reliable early Lithium spots. You need two successful scans of the device fragments to synthesize the recipe.
The Great Jaw is dangerous to harvest. Its pinkish internal tendons act as a trigger — brush them and the jaw snaps shut, flooding the interior with acid that will kill you before you can swim out. Move slowly, line up each scan, and back out the way you came.
Recipe and build requirements
Once both fragments are scanned, the PDA confirms with a "Portable Oxygen Generator Unlocked" prompt and adds the recipe to your Habitat Builder, not the Fabricator. It builds as a Base Module / Utility deployable.
| Property | Value |
|---|---|
| Build tool | Habitat Builder |
| Materials | 3 Titanium, 2 Lithium |
| Power source | 1 Basic Battery |
| Category | Utility / Base Module (deployable) |
| Blueprint source | Fragment scans inside a Great Jaw |
How it works underwater
The generator can be carried by hand like a Portable Locker, or clipped onto a hardpoint such as the back of a Tadpole or a Dive Elevator. It slowly refills its internal oxygen reserve through electrolysis as long as the battery has charge.
Output depends on how full the internal reserve is when you trigger it. A nearly full unit gives roughly +15 oxygen per use, while a barely-charged one returns about +5. The fill rate works out to around 4 units of oxygen every 10 seconds, and there's no on-screen meter showing how much is currently stored.
A fully charged Basic Battery only covers a handful of uses before it drains, so plan to keep spare batteries on a tool belt slot if you intend to rely on the generator for long traversals.
When it's worth using
The Portable Oxygen Generator fills a narrow role. It's most useful in the window after you've left the safety of bases and Oxygen Tunics but before you've unlocked stronger options like the Standard Air Tank, High Capacity Air Tank, Rebreather, or the Tadpole vehicle, which itself replenishes oxygen while you're inside.
Once the Tadpole is built and you have an upgraded air tank, the generator becomes situational — useful for stationary scanning runs deep in a cave where you'd rather not surface, or mounted on a hardpoint as a refill station near a dive site.
Confirming the unlock
You'll know the blueprint is registered when two notifications appear in the left-hand log: "Builder Tool (New Blueprint Synthesized)" followed by "Portable Oxygen Generator Unlocked!" If only one fragment scan is completed, the entry stays at 1 / 2 progress, and the device won't appear in the Habitat Builder menu under utility modules. Return to a Great Jaw and scan a second fragment to finish it.
Subnautica 2 remains in early access, so material costs, scan counts, and generator output rates can shift between patches. The Great Jaw remains the consistent blueprint source for now, and pairing the trip with a Lithium haul keeps the detour efficient.