High Capacity O₂ Tank (Subnautica)

The High Capacity O₂ Tank is an upgrade to the Standard O₂ Tank that is crafted at the Fabricator, being the only upgrade not requiring a Modification Station.

It can only be crafted after the player has acquired a Standard O₂ Tank.

Overview

Attribute	Value
Description	O₂ mix. Highly Compressed breathable air.
Build Time	5 seconds
Size	6 (2×3)
Perks	Higher air capacity
Penalties	-0.4 m/s underwater, -0.53 m/s surface
Debug Spawn	`doubletank`

While equipped, it boosts the player's maximum Oxygen supply by 90 units for a total of 135 units, but slows their non-Seaglide Swimming Speed by -0.4 m/s underwater and -0.53 m/s on the surface.

The player must equip the High Capacity O₂ Tank in the tank slot of the Paperdoll UI in order to benefit from it. While not equipped, it takes six slots (2×3) in the inventory.

Upgrades

It can be upgraded to the Lightweight High Capacity Tank or the Ultra High Capacity Tank at the Modification Station. Neither can be upgraded into the other.

Lightweight High Capacity Tank: Carries the same oxygen as the High Capacity tank, but has only 1/4 the movement penalty.
Ultra High Capacity Tank: Has twice the oxygen of the High Capacity, but a 50% greater swimming penalty, and is the only tank with speed penalty when in inventory as well as when equipped in a Paperdoll slot.

When an O₂ tank of any kind is fabricated or upgraded, it defaults to being empty and it must be equipped in an atmosphere to fill it. This is important if the player intends to carry multiple tanks for deep diving without a vehicle.