What to know
- The Tadpole Pens is one of the most important mid-game story objectives in Subnautica 2.
- You need a hidden keycode found in nearby thermal caverns to unlock the facility.
- Heat resistance upgrades and extra oxygen preparation are strongly recommended before entering.
- Completing the area unlocks major Tadpole vehicle progression and blueprint scans.
After progressing through several black box investigations in Subnautica 2, you eventually receive the “Investigate Tadpole Pens” objective. This mission becomes a major turning point because it introduces deeper biome exploration, advanced vehicle systems, and tougher environmental hazards.
The biggest obstacle is the locked Tadpole Pens facility door, which requires a special keycode hidden in nearby volcanic caverns. The area is confusing at first, especially because of the heat damage zones and maze-like underwater tunnels. Here is the complete walkthrough from preparation to finishing the objective.
| Quick Overview | Details |
|---|---|
| Main Objective | Investigate the Tadpole Pens |
| Recommended Depth | 300m+ |
| Major Hazard | Extreme heat zones |
| Required Tool | Scanner |
| Strongly Recommended | Heat adaptation upgrade |
| Key Reward | Tadpole-related blueprints |
| Key Difficulty | Finding the hidden keycode |
Preparing before entering the Tadpole Pens zone
Before attempting this mission, you should already have:
| Recommended Equipment | Why It Helps |
|---|---|
| High Capacity O2 Tank | Longer cave exploration |
| Heat Resistance Adaptation | Prevents rapid heat damage |
| Seaglide or Wavemaker | Faster traversal |
| Scanner | Required for blueprint scans |
| Medical Kits | Heat and creature damage |
| Extra Water | Long exploration section |
The thermal biome surrounding the Tadpole Pens is extremely punishing if you enter too early. Many players reach the objective marker before they are actually prepared to survive there.
You will notice rising temperatures, lava vents, and aggressive wildlife once you descend deeper into the region. The heat resistance adaptation dramatically reduces the difficulty of this mission.
Where the Tadpole Pens are located
The Tadpole Pens are located deep inside a volcanic trench region connected to the mid-game story progression. The structure itself sits near heated cavern systems and alien industrial wreckage.
You usually approach the area after following NOA transmissions and black box coordinates. The entrance is recognizable because of the large industrial facility door embedded into rock formations surrounded by thermal vents.
The door is locked when you first arrive.
How to find the Tadpole Pens keycode
The keycode is not located inside the facility itself. Instead, you must explore a nearby thermal cave network roughly 300 meters away from the locked entrance.
How the cave system works
The nearby cave area contains:
- Narrow volcanic tunnels
- Heat geysers
- Oxygen pressure sections
- Damaged research equipment
- Data terminals
You are searching for a terminal containing the Tadpole Pens access code.
How to reach the keycode terminal
Step 1
Head away from the locked Tadpole Pens entrance and look for a descending thermal trench nearby.
You should notice glowing orange cracks and steam vent activity.
Step 2
Descend carefully while avoiding direct contact with the hottest vent openings.
Heat damage ramps up quickly in this section.
Step 3
Follow the cave until you locate damaged research platforms and abandoned equipment.
The area contains several dead-end tunnels, so stay close to illuminated pathways.
Step 4
Find the small research terminal inside the cavern structure.
Interact with the terminal to automatically obtain the Tadpole Pens keycode.
Step 5
Return to the locked facility entrance and input the code on the keypad.
The Tadpole Pens door will permanently unlock.
Entering the Tadpole Pens facility
Once inside, the mission becomes much easier. The interior contains several important scans and story-related discoveries.
You should thoroughly explore every room because this facility contains valuable progression unlocks tied to the Tadpole vehicle system.
Important things to scan inside the Tadpole Pens
| Blueprint/Scan | Importance |
|---|---|
| Tadpole Vehicle | Essential submarine unlock |
| Tadpole Dock | Vehicle docking system |
| Vehicle Fabricator | Advanced crafting progression |
| Data Terminals | Story progression |
Several scans inside this facility are mandatory for unlocking future crafting options. Missing one often forces players to return later. This facility is one of the earliest reliable locations for unlocking core Tadpole progression systems.
How to fully complete the Tadpole Pens objective
Unlock the door using the retrieved keycode. Explore every accessible room. Scan all Tadpole-related machinery and fragments. Collect all PDA logs and data entries.
Exit the facility after your objective updates.
The mission normally completes automatically after scanning the necessary technology and progressing the investigation logs.
Rewards and unlocks from the Tadpole Pens
| Reward | Use |
|---|---|
| Tadpole Blueprint Progress | Unlocks vehicle crafting |
| Vehicle Dock Components | Base expansion |
| Story Logs | Main narrative progression |
| Advanced Fabrication Unlocks | Mid-game crafting access |
The Tadpole itself becomes one of the most useful exploration vehicles in the current version of the game because it allows safer deep-biome travel and extended oxygen management.
Common mistakes players make during this mission
One of the biggest mistakes is attempting the area too early without heat resistance upgrades. The thermal damage can drain health faster than expected, especially while searching for the keycode terminal.
Another issue is forgetting to bring enough oxygen support. The caves around the keycode location are deeper and longer than they initially appear.
Players also frequently miss scans inside the facility and later realize they cannot craft important vehicle components.
The Tadpole Pens objective can feel intimidating initially because of the thermal hazards and hidden keycode mechanics, but it becomes manageable once you prepare properly. The mission rewards are absolutely worth the effort because they unlock some of the most important mid-game progression systems in Subnautica 2.
This mission effectively acts as the gateway into deeper progression systems in Subnautica 2. After completing it, exploration opens up dramatically thanks to the Tadpole vehicle path and deeper biome access.
Many later objectives assume you already completed this facility and unlocked the related blueprints.
