What to know
- Isotonic Water is a stronger hydration item than regular Water.
- The recipe unlocks after you scan or obtain a Flash Slug.
- Crafting requires 1 Flash Slug and 1 Salt.
- Each bottle restores 55 hydration, compared to 40 hydration from regular Water.
Subnautica 2 offers several ways to stay hydrated, but Isotonic Water is one of the most efficient options available early in the game. Once you unlock the recipe, it becomes a reliable resource for deeper expeditions where carrying fewer supplies can make a big difference.
| Quick Overview | Details |
|---|---|
| Item | Isotonic Water |
| Crafting Station | Fabricator |
| Recipe | 1× Flash Slug + 1× Salt |
| Hydration Restored | 55 Water |
| Recipe Unlock | Scan or obtain a Flash Slug |
| Best Use | Long exploration trips and deep dives |
Where to find Flash Slugs in Subnautica 2
Flash Slugs can be found beyond the trench area. Start your journey from the Alien Ruins and follow the large purple roots descending toward the Angel Comb biome. As you explore this route, keep an eye out for Flash Slugs and collect or scan one when you find it. Doing so unlocks the Isotonic Water blueprint in your Fabricator.
How to make Isotonic Water in Subnautica 2
Step 1
Travel beyond the trench and head toward the Angel Comb biome by following the large purple roots from the Alien Ruins.
Step 2
Locate a Flash Slug and scan or collect it. This unlocks the Isotonic Water recipe in your Fabricator.
Step 3
Collect one unit of Salt. Salt is a common crafting material found throughout the ocean floor and is used in several survival recipes.
Step 4
Return to your base or Lifepod and access the Fabricator.
Open the Sustenance section and craft Isotonic Water using:
| Ingredient | Quantity |
|---|---|
| Flash Slug | 1 |
| Salt | 1 |
The Fabricator will produce one bottle of Isotonic Water.
Why Isotonic Water is worth using
Regular Water crafted from Water Slugs restores 40 hydration, while Isotonic Water restores 55 hydration. This makes it significantly more efficient when inventory space is limited and you’re planning extended trips away from your base.
| Water Type | Hydration Restored |
|---|---|
| Water | 40 |
| Isotonic Water | 55 |
Because it provides more hydration per inventory slot, many players switch to Isotonic Water as their primary drinking supply once Flash Slugs become accessible.
Isotonic Water rewards and benefits
| Benefit | Description |
|---|---|
| Higher Hydration | Restores 55 Water |
| Inventory Efficiency | More hydration per slot |
| Better for Exploration | Ideal for long-distance dives |
| Easy Crafting | Requires only two ingredients |
Once unlocked, Isotonic Water should become a regular part of your survival kit. The extra 15 hydration compared to standard Water may seem small at first, but over multiple dives it greatly reduces the number of bottles you need to carry, leaving more inventory space for resources and rare materials.
If you’re looking for the best early-to-mid game hydration source in Subnautica 2, Isotonic Water is an excellent upgrade. Simply find and scan a Flash Slug beyond the trench near the Angel Comb biome, gather some Salt, and craft the drink at your Fabricator. The resulting 55 hydration makes it one of the most efficient water sources currently available in the game.
