Survival Basics: Oxygen, Hunger, and Health
Learn the core survival mechanics of Subnautica 2 including oxygen management, hunger and thirst, and health systems.
Your journey on this alien ocean planet begins with mastering three critical survival resources: Oxygen, Hunger & Thirst, and Health. Understanding how these systems work is the difference between thriving and an early grave.
Oxygen Management
Oxygen is your most critical resource. When you run out, you take damage until you either reach air or perish.
How Oxygen Works
- Your starting oxygen capacity is 45 seconds
- Oxygen depletes faster when swimming quickly or using the Seaglide
- Oxygen recharges automatically at the surface or inside bases/vehicles
- A warning sound plays at 15 seconds remaining
Extending Oxygen
| Method | Oxygen Bonus | How to Unlock |
|---|---|---|
| Standard Tank | +30s | Craft with Fiber Mesh + Titanium |
| High Capacity Tank | +90s | Scan fragments in Kelp Forest |
| Ultra High Capacity Tank | +180s | Modification Station upgrade |
| Rebreather | Reduces consumption at depth | Craft with Fiber Mesh + Rubber |
Pro Tip: Always carry a backup Oxygen Tank in your inventory. You can swap it mid-dive for an instant refill!
Hunger & Thirst
Your character needs regular food and water to survive. Letting either reach zero causes health damage.
Food Sources
| Source | Food Value | Notes |
|---|---|---|
| Peepers | +12 food | Cook in Fabricator |
| Boomerang | +15 food | Common, easy to catch |
| Reginalds | +25 food | Best early-game food |
| Nutrient Blocks | +50 food | Found in supply crates |
| Marblemelon | +8 food | Can be grown in base |
Water Sources
| Source | Water Value | Notes |
|---|---|---|
| Filtered Water | +30 water | Fabricator - needs Salt + Coral Tube |
| Large Filtered Water | +50 water | Later game, more efficient |
| Bleach | +20 water | Crafted from Salt + Coral Tube |
| Bulbo Tree Fruit | +10 water | Can be grown in base |
Pro Tip: Build a water filtration machine in your base as soon as possible. It produces Large Filtered Water automatically.
Health System
Your health is represented by a bar in the HUD. It depletes when you take damage from creatures, environmental hazards, or oxygen deprivation.
Healing Methods
| Method | Healing | Availability |
|---|---|---|
| Medkit | +50 health | Fabricator - needs Fiber Mesh |
| Emergency Medkit | +25 health | Basic recipe |
| Time | Slow regen | Only when above 50% hunger/thirst |
| Vehicle Repair | Repair vehicle health | Vehicle Repair Tool |
Common Damage Sources
- Creature attacks - Most common in dangerous biomes
- Oxygen deprivation - Takes ~5% health per second after oxygen hits zero
- Environmental hazards - Heat, cold, acid
- Crush depth - Taking a vehicle past its crush depth
- Collision damage - High-speed impacts with terrain
Beginner Tip: Stay in the Safe Shallows for your first hour. The creatures there are mostly passive, resources are abundant, and oxygen is never far away.