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Underwater Protection Module

★★★☆☆ Mid Game

Extended underwater breathing. Chlorine + Oxygen at Exosuit upgrade station.

1. Overview

The Underwater Protection Module is an Exosuit upgrade that dramatically extends how long you can remain submerged in the oceans of No Man's Sky. While your standard Life Support provides a basic level of underwater breathing, it depletes rapidly — typically giving you only 30–45 seconds of dive time before you begin taking damage. Each Underwater Protection Module you install adds a dedicated underwater oxygen tank that extends this timer by 15–30 seconds per module, depending on the class (C, B, A, or S-class). With three S-class modules installed, you can achieve nearly 5 minutes of uninterrupted underwater exploration.

Underwater environments in No Man's Sky are some of the most biologically diverse and resource-rich areas in the game. Deep ocean trenches hide Submerged Relics (valuable trade commodities), Salvageable Scrap (refined into Scrap Metal), and rare underwater flora like Rigellium, Chrysonite, and Kelp Sac. Kelp Sac is particularly valuable — it is a required ingredient for the Stasis Device and Fusion Ignitor, the two most valuable craftable items in the game at 15.6 million Units each. Without adequate underwater protection, farming these resources becomes a frustrating cycle of surfacing, recharging, and diving again.

Beyond resources, underwater exploration is required for several questlines and milestones. The Dreams of the Deep secondary mission line takes you deep into underwater ruins and requires extended dive times to reach objectives. The base-building underwater modules (like the Nautilon Chamber and Marine Shelter) require you to spend significant time underwater for placement and wiring. The Planet Zoology milestone for discovering all fauna on a planet often includes 2–3 underwater species that can only be found in deep trenches.

The Underwater Protection Module comes in four classes: C, B, A, and S. Higher class modules provide longer underwater breathing duration and can occupy any of the three Technology slots in your Exosuit (the rightmost column of your Exosuit inventory). You can install up to three modules of the same type in adjacent slots for synergy bonuses — placing three Underwater Protection Modules next to each other provides an additional 5% bonus to the total timer beyond their individual values. This means three S-class modules in a vertical column give you the maximum possible underwater time.

Unlike most Exosuit upgrades which are purchased from the Space Station Exosuit Technology Merchant for Nanites, Underwater Protection Modules are crafted directly at the Exosuit Upgrade Station. This station is found on every Space Station to the left of the landing bay (when facing the station core). Interacting with it opens a special crafting interface where you can craft hazard protection modules, shield modules, and movement modules using specific recipes. The Underwater Protection Module recipe requires Chlorine and Oxygen — two mid-game resources that are relatively easy to acquire once you know where to look.

This guide covers everything from the exact recipe to the most efficient Chlorine and Oxygen farming routes, plus the advanced technique of using a refiner loop to multiply your Chlorine supply exponentially. By the end, you will have three S-class modules installed and the ability to stay underwater long enough to reach even the deepest ocean floors.

2. Recipe & Blueprint

The Underwater Protection Module is crafted at the Exosuit Upgrade Station aboard any Space Station. This is the cylindrical terminal to the left of the landing bay when you enter a station — it has a humanoid silhouette icon above it. Interact with the station and navigate to the Hazard Protection category to find the Underwater Protection Module recipe.

Primary Recipe

Underwater Protection Module = 250x Chlorine + 100x Oxygen

Each module crafted at the station is assigned a random class (C, B, A, or S) upon creation. The class distribution follows a weighted random roll: C-class is most common (~50%), B-class is moderately common (~30%), A-class is uncommon (~15%), and S-class is rare (~5%). This means you will likely need to craft multiple modules to get three S-class versions. Budget for crafting 15–20 modules to get a full set of three S-class. Keep all your A-class modules as well — they are a significant upgrade over nothing and can fill gaps while you farm for S-class replacements.

Recipe for a Single S-Class Set (Estimated)

To get three S-class Underwater Protection Modules, you will need to craft approximately 15–20 modules on average. Here is the total resource estimate:

Full S-Class Set (3x S-Class) ≈ 3,750–5,000x Chlorine + 1,500–2,000x Oxygen

This sounds like a lot, but the Chlorine Expansion Loop technique described in the Route section can produce thousands of Chlorine from a small starting amount. With the loop, your actual farming requirement drops to roughly 100 Chlorine and 200 Oxygen — the refiner does the rest.

Exosuit Upgrade Station Location

The Exosuit Upgrade Station is located on the left side of every Space Station, immediately visible when you exit your starship and face the station core. It is a tall cylindrical terminal with a blue holographic silhouette floating above it. If you are having trouble finding it, look for the NPC standing nearby — the Exosuit vendor will offer to sell you additional inventory slots for increasingly high prices. The crafting interface is accessed by interacting with the terminal itself, not the NPC.

Adjacency Bonus Explained

No Man's Sky uses an adjacency bonus system for Exosuit, Starship, and Multi-Tool upgrade modules. When you place three modules of the same type next to each other (forming a horizontal row or vertical column), each module receives a synergy boost indicated by a colored border. For Underwater Protection Modules:

  • No adjacency: Base timer only (e.g., 30s for S-class)
  • 2 adjacent modules: ~3% bonus to both adjacent modules
  • 3 adjacent modules: ~5% bonus to all three modules

To maximize your underwater time, place all three Underwater Protection Modules in a vertical column in your Exosuit's Technology slots. The Technology slots are the rightmost column of your Exosuit inventory grid. If you have not yet unlocked all Technology slots, the Exosuit vendor NPC will sell them to you for Units — the first slot costs 5,000 Units and prices increase for each subsequent slot up to a maximum.

3. Materials & How to Get Them

Complete Material Checklist

🧪 Chlorine

Total needed: 3,750–5,000 (or ~100 with expansion loop)

Source 1: Refine Salt 2:1 in Medium/Large Refiner

Source 2: Mine Chlorine deposits on Toxic/Ocean planets

Source 3: Chlorine Expansion Loop (see Route section)

Notes: Green-tinted mineral deposits. Salt is found in underwater minerals on ALL ocean planets.

💨 Oxygen

Total needed: 1,500–2,000

Source 1: Red flowering plants on most planets (Oxygen-Rich Plant)

Source 2: Purchase from Galactic Trade Terminals (~150 Units each)

Source 3: Refine Kelp Sac or Fungal Mould 1:2 in refiner

Notes: The most reliable method is harvesting Oxygen-Rich Plants — they give 50–80 Oxygen each and respawn quickly.

🧂 Salt

Total needed: 7,500–10,000 (if not using expansion loop)

Source: Underwater mineral deposits on ALL ocean/water planets

Tool: Mining Beam or Terrain Manipulator

Notes: Salt deposits are the white/crystal underwater formations. Extremely abundant. Refine 2 Salt → 1 Chlorine.

🔄 Chromatic Metal (Optional)

Total needed: 100 (for Oxygen refiner loop)

Source: Refine Copper, Cadmium, Emeril, or Indium

Notes: Only needed if doing the advanced Chlorine Expansion Loop. Copper is found on most planets.

Farming Chlorine: The Three Methods

There are three viable methods for acquiring Chlorine, listed from most to least efficient:

  1. Chlorine Expansion Loop (BEST): Place 1 Chlorine + 2 Oxygen in a Medium or Large Refiner. The output is 6 Chlorine. You created 5 extra Chlorine from nothing but Oxygen. Take those 5 Chlorine, add 10 more Oxygen, and get 30 Chlorine. Repeat. This exponential loop turns 1 Chlorine and sufficient Oxygen into thousands of Chlorine. Details in the Route section.
  2. Salt Refining: Dive to any ocean planet and mine Salt from underwater mineral deposits. 2 Salt refines into 1 Chlorine in any refiner. Salt is extremely abundant underwater — a 10-minute dive can yield 1,000+ Salt, which becomes 500+ Chlorine.
  3. Direct Mining: Some toxic and ocean planets have direct Chlorine deposits on land (green-tinted mineral formations). These are less common than Salt deposits but provide Chlorine without the refining step. Use your Analysis Visor to scan for them.

Farming Oxygen: The Two Best Spots

Oxygen is one of the easiest resources to acquire in large quantities. The two best methods are:

  1. Oxygen-Rich Plants: These red flowering plants are found on virtually every planet type. Use your scanner and look for red plant icons. Each plant yields 50–80 Oxygen when harvested with your Multi-Tool. They respawn every few minutes. A single field of 10 plants can be farmed in a loop indefinitely. Mark a good spot with a Save Beacon for repeated farming.
  2. Purchase from Trade Terminals: Oxygen is sold at Galactic Trade Terminals on space stations and at minor settlements for approximately 150 Units each. If you have a solid income source (like selling Cobalt or Storm Crystals), buying Oxygen is faster than farming. Trade terminals stock 500–2,000 Oxygen at a time.

4. Optimal Farming Route

This route is optimized for players who want three S-class Underwater Protection Modules as quickly as possible. The route uses the Chlorine Expansion Loop to minimize farming time and leverages the best-known farming locations. Total estimated time: 45–60 minutes.

Phase 1: Initial Resource Gathering (15 minutes)

  1. Warp to an Ocean Planet — Use the Galaxy Map to find a system with at least one planet that shows 'Water' or 'Ocean' in its description. Paradise planets and Lush planets often have extensive oceans. The planet type does not matter as long as it has deep water.
  2. Land near the coast — Find a shoreline with easy access to both land and deep water. You want a flat area where you can place a portable refiner.
  3. Deploy a Portable Refiner — Open the Build Menu (Z), navigate to Portable Technology, and place a Portable Refiner on the shore. You will need 30 Oxygen + 1 Metal Plating to build it.
  4. Harvest Oxygen — While on land, scan for and harvest Oxygen-Rich Plants (red flowering plants) until you have at least 500 Oxygen. Mark this spot with a Save Beacon for later returns.
  5. Dive for Salt — Equip your Hazard Protection modules, dive into the water, and mine Salt from the white crystalline underwater formations. Collect 200 Salt. Salt deposits are everywhere underwater — look for the glowing white pillars on the seafloor.
  6. Refine Salt into Chlorine — Return to shore, interact with your Portable Refiner, and refine 200 Salt into 100 Chlorine. This is your seed stock for the expansion loop.

Phase 2: Chlorine Expansion Loop (20 minutes)

This is the core technique that makes farming Underwater Protection Modules trivial. The loop exploits the refiner recipe that produces more Chlorine than it consumes:

Chlorine Expansion Loop: 1 Chlorine + 2 Oxygen → 6 Chlorine (Medium/Large Refiner)

  1. Build a Medium Refiner — If you do not have one yet, craft it at your base (requires 100 Chromatic Metal + 50 Di-hydrogen Jelly). Place it next to your Portable Refiner on the shore.
  2. Start the Loop — Put your 100 Chlorine seed stock into the Medium Refiner input. Add 200 Oxygen. The refiner will output 600 Chlorine.
  3. Expand — Take 100 of your new Chlorine, add 200 more Oxygen → 600 Chlorine output. You now have 1,100 Chlorine.
  4. Repeat — Continue the loop. Each cycle multiplies your Chlorine by approximately 5x (after subtracting the seed). After 4–5 cycles, you will have 5,000+ Chlorine — enough for your full S-class set.
  5. Replenish Oxygen as needed — If you run low on Oxygen, harvest more from nearby red plants or purchase from the local trade terminal/minor settlement.

The math works because each cycle consumes 1 Chlorine + 2 Oxygen and produces 6 Chlorine — a net gain of 5 Chlorine per cycle per unit of input. With a starting 100 Chlorine and 1,000 Oxygen, you can produce 3,000+ Chlorine. This is the same technique used by endgame players to farm Chlorine for massive Unit sales (Chlorine sells for approximately 600 Units each to trade terminals).

Phase 3: Gather Additional Oxygen (10 minutes)

  1. Farm Oxygen-Rich Plants — While your Chlorine stock is building, spend time harvesting Oxygen. You need roughly 2,000 Oxygen for the full module crafting set.
  2. Alternative: Buy Oxygen — If you have excess Units, fly to a space station and purchase Oxygen from the Galactic Trade Terminal. Each terminal stocks 500–2,000 Oxygen at ~150 Units each.
  3. Alternative: Atmospheric Harvester — If you have unlocked the Atmospheric Harvester blueprint, place one at your base on a planet with Oxygen atmosphere. It passively generates Oxygen over time.

Phase 4: Craft at the Exosuit Upgrade Station (10 minutes)

  1. Warp to any Space Station — All stations have the Exosuit Upgrade Station.
  2. Locate the Upgrade Station — Left side of the station, blue holographic silhouette icon.
  3. Craft in batches — Open the crafting interface, navigate to Hazard Protection → Underwater Protection Module. Craft 5 modules at a time. Check their classes — keep any S-class and A-class, discard C-class and B-class (or keep them as temporary placeholders).
  4. Repeat until three S-class — With 5,000 Chlorine and 2,000 Oxygen, you can craft 20 modules. Statistically, this should yield 1 S-class module. You may need to do a second farming run to get all three S-class modules — this is normal and expected.
  5. Install modules — Open your Exosuit inventory, switch to the Technology tab (rightmost slots), and place your best three Underwater Protection Modules in a vertical column for the adjacency bonus.

Phase 5: Test Your New Gear

  1. Find an ocean planet — Warp to any system with a water world.
  2. Dive deep — Jump in and watch your underwater timer. With three S-class modules, you should have 4–5 minutes of dive time.
  3. Farm Kelp Sac — While underwater, look for Kelp Sac (glowing green underwater plants). These are required for Stasis Devices and sell for 40,000 Units each raw. With your extended timer, you can now efficiently farm deep-ocean Kelp Sac patches.

5. Gotchas & Pro Tips

⚠️ Random Class Rolls

Every Underwater Protection Module you craft has a random class assignment. There is no way to guarantee an S-class module on any single craft. The approximate odds are: C-class ~50%, B-class ~30%, A-class ~15%, S-class ~5%. This means on average you need to craft 20 modules to get one S-class, and 60 modules for a full three-S-class set. Budget your resources accordingly. Many players settle for A-class modules (which provide ~80% of the S-class benefit) to save farming time.

⚠️ Technology Slot Limit

Your Exosuit has a limited number of Technology slots — typically 7–14 depending on how many you have purchased from Exosuit vendors. Underwater Protection Modules compete for these slots with Movement Modules, Shield Modules, Thermal Protection Modules, Radiation Protection Modules, Toxic Protection Modules, and Jetpack upgrades. Plan your layout carefully. A common approach is to dedicate one column (3 slots) to underwater modules, one column to shield/movement, and one column to hazard protection.

⚠️ Cannot Be Repaired

If you die and your Exosuit Technology slots are damaged, Underwater Protection Modules can break and must be re-crafted. Unlike purchased modules which can sometimes be repaired with resources, crafted modules are destroyed when their slot is damaged. Always carry backup resources (250 Chlorine + 100 Oxygen) if you are exploring hostile environments where death is likely.

⚠️ Life Support Still Drains on Land

Underwater Protection Modules only extend your underwater breathing timer. They do not affect your Life Support drain while walking on land or flying with your jetpack. Do not confuse them with Life Support Modules, which are a separate upgrade line purchased from the Exosuit Technology Merchant with Nanites.

⚠️ Does Not Stack With Life Support Gel

Using Life Support Gel or Oxygen capsules while underwater will refill your Life Support bar but does not reset the underwater timer. The underwater timer is a separate mechanic from Life Support. Once your underwater protection runs out, you begin taking damage regardless of your Life Support level. The only way to reset the underwater timer is to surface and breathe air.

💡 Pro Tip: The Nautilon Submarine Is Even Better

If you find yourself spending a lot of time underwater, build a Nautilon Chamber and summon the Nautilon submarine exocraft. The Nautilon provides infinite underwater time (no oxygen limit), has its own high-powered mining laser, and can be upgraded with sonar and high-beam headlights. It requires the Nautilon Chamber blueprint (from the Construction Research Station) and its own set of upgrade modules. Consider the Underwater Protection Modules as your stepping stone to the Nautilon.

💡 Pro Tip: Mark Oxygen Farms

When you find a planet with dense fields of Oxygen-Rich Plants, place a Base Computer and claim a small base there. Build a Teleporter and connect it to power. Now you have a permanent fast-travel point for Oxygen farming that you can return to anytime from any space station teleporter. This dramatically reduces farming time for future Underwater Protection Module crafting sessions.

💡 Pro Tip: Sell Excess Chlorine for Profit

If you use the Chlorine Expansion Loop, you will likely produce far more Chlorine than you need for the modules. Do not discard it — Chlorine sells for approximately 600 Units per unit to Galactic Trade Terminals. A single expansion loop session producing 10,000 Chlorine translates to 6 million Units. Many experienced players use this exact loop as their primary early-to-mid game income source, even before they have access to Stasis Device or Fusion Ignitor crafting.

6. Free Benefits & What This Unlocks

Installing Underwater Protection Modules opens up an entire category of gameplay that is otherwise frustrating and time-limited. Here is everything you gain:

Immediate Benefits

  • Extended Dive Time: With three S-class modules, your underwater timer extends from ~45 seconds to nearly 5 minutes. This is enough to reach the ocean floor on most planets, explore underwater caves, and collect distant resources without frantic surfacing.
  • Stress-Free Exploration: No more watching the drowning countdown while frantically swimming toward the surface. With extended protection, underwater exploration becomes as relaxed as walking on land.
  • Deep Treasure Access: Submerged Relics, Salvageable Scrap, and sunken technology modules are often found in the deepest trenches. With proper underwater protection, you can reach these without taking damage.

Unlocked Activities

  • Kelp Sac Farming: Kelp Sac is a key ingredient in the Stasis Device and Fusion Ignitor (15.6 million Units each). Kelp Sac only grows underwater and is most abundant in deep ocean trenches. With three S-class modules, you can efficiently farm enough Kelp Sac for multiple crafting runs. Each Kelp Sac sells for ~40,000 Units raw.
  • Dreams of the Deep Mission: This secondary questline requires extensive underwater exploration including swimming through submerged ruins, retrieving artifacts from the seafloor, and battling underwater creatures. Without adequate protection, this mission is extremely difficult. With three S-class modules, it becomes a relaxing sightseeing tour.
  • Abyssal Horror Hunting: Deep oceans are home to Abyssal Horrors — terrifying creatures that guard valuable resources. With extended dive time, you can lure them away from their hoards, grab the loot, and escape before your protection runs out. The resources they guard include Larval Cores (worth ~90,000 Units) and Hadal Cores (worth ~120,000 Units).
  • Underwater Base Building: Building bases underwater requires spending significant time submerged to place structures, run power lines, and install underwater glass tunnels. Extended protection makes this process far more enjoyable. Underwater bases are among the most visually stunning in the game, with glass corridors offering panoramic ocean views.
  • Fauna Discovery: Many planets require discovering underwater species to complete the Zoology milestone. These creatures are often deep-dwelling and require extended dive times to locate and scan.

Economic Benefits

  • Chlorine Resale: As detailed in the Pro Tips, the Chlorine Expansion Loop used to farm for these modules generates massive quantities of Chlorine as a byproduct. Selling excess Chlorine to trade terminals is a reliable income stream.
  • Underwater Commodity Trading: Submerged Relics refine into valuable trade commodities. Salvageable Scrap becomes Scrap Metal (worth ~50,000 Units per stack). A dedicated underwater salvage run with proper protection can yield 2–3 million Units in an hour.
  • Nautilon Unlock Path: Building Underwater Protection Modules familiarizes you with ocean exploration, which is the prerequisite for unlocking the Nautilon submarine. The Nautilon in turn unlocks deep-sea exocraft missions from your freighter command room, which reward valuable items including Starship and Multi-Tool upgrade modules.