Guide Steps
Step 1: Gather Titanium for the Air Tank
Collect 2 metal salvage from the Shallows seafloor. Process in the fabricator: salvage → 4 Titanium each. You need only 2 Titanium for the Air Tank. The remaining salvage material can go to other tools and base construction.
Step 2: Find Lucifer Rotsac and craft Rubber
Rubber = 2 Lucifer Rotsac. Lucifer Rotsacs are found in caves — they are small, round, reddish-brown sacs attached to cave walls and floors. Collect 2 Rotsacs. Process in the fabricator: 2 Lucifer Rotsac → 1 Rubber. You need 1 Rubber for the Air Tank.
Step 3: Farm Silver from caves
Silver is found in caves approximately 290-350m north of the Lifepod at ~35m depth. You need 2 Silver for the Standard Air Tank. This is the hardest material to get for this recipe — plan a dedicated silver run. Silver deposits are grayish-white metallic veins on cave surfaces.
Step 4: Craft the Air Tank
Fabricator → Equipment → Standard Air Tank. Recipe: 2 Titanium + 1 Rubber + 2 Silver. The Air Tank goes in a body slot. It adds +30 oxygen, taking you from 45 seconds to 75 seconds of dive time. Equip it immediately — this is your highest-impact early upgrade.
Upgrade path to High Capacity and Ultra High Capacity
Standard Air Tank (+30 O2, 45→75 total) → High Capacity Air Tank (1 Std Tank + 1 Plasteel Ingot, requires Modification Station) → Ultra High Capacity (1 High Cap + 3 Troilite + 3 Atacamite). Note: Ultra High Capacity is announced but currently unavailable in Survival mode as of EA launch. Each upgrade stacks with the Rebreather for maximum depth exploration.