Subnautica 2: How to Get the High Capacity Air Tank (Oxygen Upgrade)

TL;DR

• The High Capacity Air Tank boosts your oxygen from 75 seconds to 120 seconds — a +75 second increase.
• The blueprint is on a Recipe Data Card inside a wreck about 280 to 290 meters southwest of the Lifepod, at around 87 to 90 meters depth (Cicada Wreck / Spires Wreck 1).
• You cannot craft it at the Lifepod Fabricator. You need a fully functional Fabricator in your own base.
• Crafting it requires: 1x Standard Air Tank + 1x Plasteel Ingot.
• The Plasteel Ingot needs 2x Titanium + 1x Lithium, processed in a Processor.
• There is a free piece of Lithium sitting on a table just outside the wreck — grab it on the same dive.
• This is one of the best early upgrades in the game. Get it as soon as possible.

The High Capacity Air Tank in Subnautica 2 is the oxygen upgrade that changes everything. Running out of air is one of the most frustrating things in the early game, and the default Standard Air Tank gives you just 75 seconds underwater. That is enough to scrape by, but not enough to explore comfortably. This guide walks you through the exact location of the blueprint, how to craft the Plasteel Ingot you need, where to find Lithium without a long grind, and the full step-by-step crafting process.

If you are just getting started and have not built a base yet, you will need one before you can craft this upgrade. See our guide on how to unlock the Habitat Builder and start building a base first.

What Is the High Capacity Air Tank?

The High Capacity Air Tank (HCAT) is a direct upgrade to the Standard Air Tank. It slots into the same equipment slot and increases your total oxygen supply from 75 seconds to 120 seconds — adding a full 75 extra seconds of underwater time.

That extra breathing room fundamentally changes how every dive feels. Wrecks, caves, and longer routes that were previously impossible without frequent resurfacing become genuinely explorable. It is not just a quality of life upgrade — it opens up mid-game areas that you simply cannot access on the Standard Air Tank alone.

For a full breakdown of every way to improve your oxygen in Subnautica 2, see our oxygen upgrade guide.

What You Need Before You Start

Before heading out, make sure you have a few things in place:

• A Standard Air Tank already crafted. The High Capacity Air Tank is an upgrade, not a standalone item. You need the base version first. Craft it at any Fabricator using 2x Titanium, 2x Silver, and 1x Rubber.
• A base with a working Fabricator. The Lifepod’s built-in Fabricator cannot craft the High Capacity Air Tank. You need your own base with a fully functional Fabricator installed.
• A base with a Processor. You need a Processor to craft the Plasteel Ingot. If you have not built one yet, see our guide on how to get Strong Acid — it covers the Processor blueprint location at the Old Habitat in detail.
• Enough oxygen for an 87 to 90 meter dive. The wreck entrance sits at depth. Even with the Standard Air Tank, this is tight. Bring Air Bladders if you have them, and consider unlocking the Wakemaker before making the trip.

You can find Silver for the Standard Air Tank and Titanium relatively close to the Lifepod. Get both crafted and sorted before heading southwest.

High Capacity Air Tank Blueprint Location

The blueprint is stored on a Recipe Data Card inside a wreck. You do not need to scan any objects — you just need to find and interact with the card.

There are two confirmed locations where the Data Card can be found:

• Cicada Wreck (Canteen / Stairway to Heaven) — approximately 280 meters southwest of the Lifepod, at a depth of around 87 to 90 meters. This is the earliest and most accessible location.
• Spires Wreck 1 — a second confirmed location if you happen to pass through that area.

The Cicada Wreck southwest of the Lifepod is the one you want for your first playthrough. It is the closest and does not require any special adaptations or upgrades to reach.

How to Get There

1. From your Lifepod, head southwest on approximately Bearing 210.
2. Swim straight for about 280 meters.
3. Descend to around 87 to 90 meters depth.
4. Look for the wreckage. Note that the Great Jaw Clam Leviathan is very close to this area — stay alert. Our Clam Leviathan guide explains how it behaves and how to avoid triggering it.
5. There is also a Colonist Bunker built into the cliffs nearby — slightly north-northwest of the wreck. It has a breathable atmosphere inside, making it an excellent staging point to refill your oxygen before going deeper into the ruins.

Inside the Wreck

Once inside the Cicada Wreck, turn left and look for a case sitting on a console. That is the Recipe Data Card. Interact with it and the High Capacity Air Tank blueprint is added to your Fabricator automatically. Be aware of electrical jellyfish-like hazards floating around inside the wreck — do not drift into them.

How to Get the Free Lithium Right Next to the Wreck

Lithium is one of the rarer early-game resources in Subnautica 2, and you need one piece of it to craft the Plasteel Ingot. The good news is that you do not need to hunt for it at all on this trip.

After collecting the Data Card, exit the wreck and look for a metal structure with a table at the center. There is a single Lithium chunk sitting in a small coral shell on that table. Pick it up before you surface.

That single piece is all you need for the Plasteel Ingot. Larger Lithium deposits are found around Thermal Vents further east and near the Tadpole Pens, but those areas require the Heat Tolerance Trait to survive. For this upgrade, the table spawn handles everything.

If you ever need more Lithium later in the game, our full guide to finding Lithium in Subnautica 2 covers every location in detail.

How to Craft the Plasteel Ingot

The High Capacity Air Tank requires 1x Plasteel Ingot. This is a refined material — you cannot make it in the Fabricator. You need a Processor in your base.

Here is the recipe:

• Plasteel Ingot = 2x Titanium + 1x Lithium (crafted in the Processor)

Titanium is one of the most common materials in the game. You should already have plenty. Combined with the Lithium you picked up outside the wreck, you have everything you need for the Ingot the moment you get back to base.

If you need a refresher on building and powering the Processor, the guide to building Processors and crafting Ingots has full details. Also make sure your base has enough power running before you start. See our guide on how to add power to your base if anything is offline.

How to Craft the High Capacity Air Tank

Once you have the blueprint, the Plasteel Ingot, and your Standard Air Tank, crafting the upgrade is straightforward.

1. Go to your base Fabricator — not the Lifepod Fabricator. The Lifepod version cannot craft this item.
2. Find High Capacity Air Tank in the Equipment section of the crafting menu.
3. Craft it using: 1x Standard Air Tank + 1x Plasteel Ingot.
4. The tank is automatically equipped to your character after crafting. Your oxygen cap immediately jumps to 120 seconds.

You do not need to manually equip it. The moment it is crafted, it replaces your Standard Air Tank and the upgrade takes effect right away.

Full Crafting Chain at a Glance

Here is the complete chain from start to finish so you can plan your resource gathering in one go:

• Standard Air Tank — 2x Titanium + 2x Silver + 1x Rubber (crafted at any Fabricator)
• Plasteel Ingot — 2x Titanium + 1x Lithium (crafted in the Processor)
• High Capacity Air Tank — 1x Standard Air Tank + 1x Plasteel Ingot (crafted at a base Fabricator)

Total raw materials needed from scratch: 4x Titanium, 2x Silver, 1x Rubber, 1x Lithium.

If you need help finding any of these, see our guides on where to find Silver, how to get Titanium, and how to get Rubber from Lucifer Rotsac.

Tips for the Southwest Dive

• The Colonist Bunker is your friend. Use it to refill oxygen before pushing deeper into the wreck. It has a breathable atmosphere and costs nothing to use.
• Watch out for the Great Jaw. The Clam Leviathan is near this wreck. It is stationary and only attacks if you enter its shell and trigger its tendrils. Stay outside the shell and you are safe.
• Grab the Lithium on exit. Do not surface before picking up the free Lithium from the table outside. It saves you an entire separate resource run.
• Bring the Wakemaker. Moving faster underwater makes the dive significantly safer, especially at 90 meters. Learn how to make the Wakemaker before heading out.
• Avoid the electrical hazards inside. The jellyfish-like organisms inside the wreck deal electrical damage. They are easy to dodge if you move carefully. Do not rush.

What Comes After the High Capacity Air Tank?

The High Capacity Air Tank is not the final oxygen upgrade in Subnautica 2. As you progress further into the game, additional methods for extending your dive time become available — including the Rebreather, Biomods like the Oxygen Control adaptation, and other equipment that reduces oxygen consumption rate.

For the full picture of oxygen management as you move into mid and late game, see our complete guide on how to increase oxygen in Subnautica 2.

Once your oxygen is sorted, your next big progression goal is likely the Tadpole submarine. That requires a Power Cell, which in turn needs Strong Acid. After that, check out our guide on how to build the Tadpole in Subnautica 2 to unlock access to the deeper regions of Proteus.

For the most efficient early game path overall, our best early upgrades and progression path guide shows you exactly what to prioritize and in what order. And if you are still deciding how to approach the game, our Survival vs Creative Mode breakdown is worth reading before you commit to a save.

Ready to dive in? Pick up Subnautica 2 on Steam or on Xbox, and check the official Subnautica website for the latest Early Access updates.