By this point you may have already noticed a couple of kinds resource deposits that haven’t yet been discussed: Salt Deposits and Sandstone Outcrops. These two new types of resource are key to upgrading your H2O supply and O2 tank capacity.
It’s Got Electrolytes
Oddly enough, Salt Deposits are the key to upgrading your water supply. By now you might be noticing that Bladderfish are getting harder to track down, or at least a tedious and constant chore. You probably won’t want to phase them out completely just yet, but Salt Deposits provide an additional, higher-quality source of water and you’ll be finding them all over the seabed as you explore.
The other ingredient you’ll need, in order to ultimately fabricate these higher quality water bottles, are Coral Tube Samples. You have probably noticed some large, tube-shaped things on the seabed around your Lifepod. You can produce an infinite supply of Coral Tube Samples simply by chipping at one of these Giant Coral Tubes with your Survival Knife at very close range.
Once you have a Salt Deposit and a Coral Tube sample, you can combine them, through a couple of steps at the Fabricator, to ultimately produce 2 bottles of Disinfected Water (H2O: +30.) Compared to the Filtered Water bottles produced from Bladderfish (H2O: +20,) these replenish 50% more H2O per bottle.
Fabricate the Bleach
Bleach is produced by combining 1x Salt Deposit and 1x Coral Tube Sample at the Fabricator.
Fabricate the Disinfected Water
One Bleach is enough to produce 2x Disinfected Water.
Sandstone Outcrops, the Source for Tier 2 Metals
As mentioned in earlier chapters, Limestone Outcrops may contain either a Titanium or Copper Ore, and are generally the first type of metal-yielding “rock” that the player encounters because they tend to be commonly scattered on the seabed in the area around the Lifepod. Because they’re found in the same rocks, and used for the most basic early-game items, Titanium and Copper can be thought of as belonging to the same “Tier” of metals in Subnautica, which we’ll refer to as “Tier 1.”
The next tier of metals, which we’ll refer to as Tier 2, can be found by breaking open Sandstone Outcrops. These are visually differentiated from Limestone by the fact that they are darker in color and more rounded looking.
By scanning one of the outcrops with the scanner you can get an easily referenced entry in your Databank which lists the metals that can be found in this kind of rock. It turns out that the 2nd tier of metals includes Lead, Silver, and Gold.
What Tier 2 Metals Can Do For You
As you start finding Sandstone Outcrops and harvesting their Tier 2 Metals, there are a few items that they’ll enable you to fabricate.
High Capacity O2 Tank
This is the highest-priority item that the Tier 2 metals can unlock for you at this stage. Maximizing your O2 storage is critical. As soon as you find 1 Silver Ore, use it to perform this upgrade on your O2 tank.
Once you’ve collected the other materials (1x Silver Ore, 2x Glass, 4x Titanium,) you will need to unequip your Standard O2 Tank before fabricating the High Capacity O2 Tank, which will use it as a starting material.
With the Standard O2 Tank now in your inventory you’re ready to fabricate the High Capacity O2 Tank.
With the new tank equipped we now have 135s of O2 capacity, an 80% increase over the 75s we had with the Standard O2 Tank.