Cave Sulfur
Category: Raw Material
Description: SO₄Tr. Sulfur-based powder which collects within particular cave plants. Combustible underwater.
Acquired From: Sulfur Plant
Size: 1
Biomes: Safe Shallows, Safe Shallows Caves, Kelp Forest Caves
Detecting sulfur deposits in the local cave systems. Sulfur is an essential component of the repair tool. ― PDA, Dialogue
Cave Sulfur is a sulfur-based raw material which can be found in Sulfur Plants after the residing Crashfish has left. The PDA description states it has the chemical formula SO₄Tr.
Collecting Cave Sulfur
The best way to collect the Cave Sulfur is to lure the Crashfish out of the plant, evade its explosion using the Seaglide, and return to its nest for the powder.
Likewise, luring out the Crashfish and triggering it to dash towards the player will cause it to gain momentum. Swimming towards it will cause the Crashfish to overshoot and explode, dealing no damage to the player if the maneuver is executed properly.
An alternative is to use the Repulsion Cannon to push them against a wall or far away from the player, triggering their explosion which will deal no damage to the player due to the distance.
Additionally, one can use a Stasis Rifle to immobilize it. However, the Crashfish will still explode even when being frozen by the stasis field, so it is recommended to stay out of the blast radius. Destroying the Sulfur Plant will prevent the Crashfish from respawning, along with its powder.
A fifth suggestion is to use the Propulsion Cannon. Picking up the Crashfish and launching it will keep it away from the player. The Crashfish still is able to explode while being picked up.
A sixth option exists, but has a high risk of injury. It's possible to charge directly toward a nesting Crashfish and kill it with the survival knife before it explodes.
Uses In Crafting
Fabricator Recipes
| Item | Quantity | Required Materials |
|---|---|---|
 Flare | ×1 |  ×5,  ×1 |
 Battery | ×1 | ×5,  ×1 |
 Laser Cutter | ×1 | ×5,  ×1 |
Gallery
Cave Sulfur, found in the Sulfur Plant
The Crashfish, a significant threat for any players wanting to harvest the powder
Cave Sulfur In-game
Trivia
- Cave Sulfur went through a number of name changes during development, starting out called Crash Meal, next being changed to Crashfish Powder, then being changed to Crashfish Sulfuric Powder, until finally it rested on Cave Sulfur in time for release.
- The chemical formula of Cave Sulfur is given as "SO₄Tr". It is unclear if this is intended to reflect an unknown element or is simply an error. "Tr" is an obsolete notation for element 65, Terbium (now Tb), though the correct formula for the Terbium Sulfate is Tb₂(SO₄)₃.
- In addition, Terbium Sulfate in real life does not reflect its properties in Subnautica as it is actually a relatively unreactive compound used in creation of fluorescent crystals.