The oxygen bladder will keep your lungs full much, much longer than raw oxite will.
If ʏᴏᴜ wᴀɴt ᴛᴏ breᴀᴛʜᴇ eᴀsier ᴏɴ a hostile aʟɪᴇn plᴀɴet, ᴛʀʏ tʜᴇ Iᴄᴀʀᴜs ᴏxʏɢᴇɴ blᴀᴅᴅer. Tʜɪs craftᴀʙʟᴇ ɪᴛem cᴀɴ ʙᴇ ꜰɪʟʟed wɪᴛh ᴀɪʀ ᴀɴd equipped ɪɴ yᴏᴜʀ sᴘᴀᴄᴇsuɪᴛ, givɪɴg ʏᴏᴜ a sᴛᴇᴀᴅy ᴀɪʀ sᴜᴘᴘʟʏ thᴀᴛ ᴡɪʟʟ lᴀst sᴇᴠᴇʀal ɪɴ-ɢᴀᴍᴇ ᴅᴀʏs ᴡʜɪʟᴇ ʏᴏᴜ're explᴏʀɪɴg ᴀɴd ʜᴜɴᴛɪɴg ɪɴ survival ɢᴀᴍᴇ Iᴄᴀʀᴜs.
To craft the oxygen bladder, you're going to need to build a few other devices first, including an oxite dissolver, and you won't be able to do that until you've reached level 10 and have unlocked the Tier 2 tech tree. That won't take you too long, but in the meantime you'll have to get by on raw oxite ore or the Tier 1 oxidizer. I would recommend crafting the oxygen bladder as soon as you can, however, because it really makes a big difference when playing Icarus.
Here's how to craft an oxygen bladder and what you'll need to make it work.Icarus oxygen bladder: How to craft and use it
The oxygen bladder becomes available when you reach level 10 and gain access to the Tier 2 tech tree. You'll find it on the tech tree below the waterskin, which you'll need to unlock first. So, that's the first two blueprint points you'll need to spend.
You'll also need to spend a blueprint point on the crafting bench, which costs 12 fiber, 20 sticks, 50 wood, and 12 stone to build. Once it's placed in your base, you can find the oxygen bladder recipe when you interact with the bench. To craft the oxygen bladder, you'll need 20 fiber, 30 leather, and 8 bone.
You won't be able to use it yet, however. You need to spend one more blueprint point to unlock the oxite dissolver (so make sure you have at least 4 blueprint points before getting started on this). This is a really neat gadget that can efficiently turn oxite into oxygen. The oxite dissolver costs 18 wood, 24 leather, and 8 bone to build. Then you'll need to place it somewhere in your base.
When you interact with the oxite dissolver, you'll see a row of four inventory slots marked "Container." That's where you'll place your new oxygen bladder (or up to four of them at once). Below that there are two inventory slots: That's where you put your raw oxite ore. And at the bottom there's a single slot for fuel. You'll need sulfur to power your dissolver.(Image credit: RocketWerkz)
Once you have oxite, sulfur, and your bladder in place, the oxite dissolver will activate, filling the bladder with oxygen. It doesn't take long, and you'll see the round icon on the bladder fill and turn white. When the bladder is full of air, you can remove it from the machine and place it in your spacesuit slot where you normally place raw oxite.
And then you can get on with your hunting and exploring! A full oxygen bladder lasts a good long while and you probably won't need to refill it for at least a couple of in-game days, though you should top it off whenever you're at your base just to be safe. Now running out of air is something you rarely need to worry about.