(Image credit: Unknown Worlds) Increasing your O2 capacity is one of the first things you'll want to do in Subnautica 2 . After all, it gets a bit annoying having to constantly resurface to gulp in air when you're trying to accomplish basic tasks. Your overall oxygen level is the game's real progression system, determining how deep you can dive and what rare resources are in your reach. There are many different methods to boost your O2 and punch above your weight when under the sea, so here's how to acquire and use each of them. How to increase oxygen capacity in Subnautica 2 There are a number of ways to boost your oxygen, so here they are in order of when they'll be useful to you and accessible: Oxygen Tunics, Bloom Sap funnels, and air pockets You can get O2 from Oxygen Tunics or by cutting Bloom Sap out of O2-filled funnels (Image credit: Unknown Worlds) Your first port of call for breathing longer underwater is the Oxygen Tunic.…