How to Investigate the Tadpole Pens in Subnautica 2 – Keycode Location

After all the challenges and hurdles I experienced in Subnautica 2, investigating the Tadpole Pens and trying to find the Keycard to open the way to the Noa Terminal is by far the hardest so far.

Here’s a comprehensive guide on how to finish the “Investigate the Tadpole Pens” objective and also find the keycode to access the location in Subnautica 2.

How to Prepare for the Tadpole Pens Mission in Subnautica 2

Before going through this adventure, there are a few things you must have to make things a lot easier. Let’s start with the mandatory ones. First, you must get the genetic adaptation for Heat Tolerance. You can’t survive the heat in the Tadpole Pens area if you don’t get the genetic adaptation.

Second, you want an Air Bladder or two to help you ascend and give you some extra oxygen just in case. Third, you must have at least the basic equipment, like the Standard Air Tank and Basic Fins.

For the optional ones that will make things extremely easier: getting a Tadpole vehicle and the Rebreather tool. The Tadpole vehicle lets you traverse around easily, and the Rebreather helps you maintain your oxygen as much as possible in the heat.

Of course, bring your food and water because you can’t find Water Slugs in the Tadpole Pens.

If you don’t have the vehicle yet, you can follow the guide linked above. For the Rebreather, there’s a scannable Rebreather in the Cicada Metal Wreckage on the way to the Tadpole Pens. If you start from the Lifepod and head straight to the Tadpole Pens marker, there should be a massive Cicada Wreckage you’ll encounter before reaching the pens.

Go inside the Cicada Wreckage and try to find the hole on the floor near one of the containers. Go under and look through the rooms. There should be a scannable Rebreather in one of the containers, as seen in the image above. There’s also a Biobed here where you can get another inventory space upgrade.

When you get the Rebreather recipe, you’ll have to go back to your base and craft it in the Fabricator using 2x Fiber Mesh and 1x System Chip. Make sure you have those Strong Acids or Necrolei Cysts available to craft those Fiber Meshes.

Now, on to the mission.

How to Finish the Investigate the Tadpole Pens Mission in Subnautica 2

Investigating the Tadpole Pens First

After preparing for the mission, head to the Tadpole Pens marker. In the image above, you’ll find the main entrance of the Tadpole Pens habitat. Near the entrance, there should be two oxygen blooms near the entrance and to the southeast when looking directly at the entrance. This is important if you don’t have a Rebreather because you can actually still get around with an Airbladder even if your oxygen is getting depleted twice as fast without a Rebreather. Just keep exploring for a bit and use your Air Bladder for oxygen, and grab an oxygen bubble to refill both your oxygen and your Air Bladder continuously.

Now, scan all the objects inside the Tadpole Pens entrance and also interact with all the terminals. If you head left from the main entrance to actually go to the marker or objective, you’ll find a locked door with a button. When you press the button, it scans you and denies you access because it requires a keycode. This is probably why you are here.

Go back, and I suggest searching the nearby debris or detached habitats around for more blueprints and lore. There should be one on the left and the right when overlooking the Tadpole Pens by the main entrance.

Going to the Blackbox Zip Objective – Keycode Location

Now, after interacting with the objects and terminals inside the Tadpole Pens, you’ll find a new marker or signal called the Blackbox – Zip. Head to the marker, and this is where the Tadpole vehicle comes in handy because it is extremely hard to traverse this area because of the heat and depth of the cave.

There should be a massive cave system that has many entrances. Once inside, just follow the marker as it takes you deeper into the cave. It is worth noting that the exact location of the marker leads to a slit to take you deeper into the cave, and not the keycode itself. There’s a terminal at the exact marker, so pick it up for lore, but this doesn’t give you the keycode. Go through this and look even deeper until you see the massive purplish roots.

Grab the box and scan the Thermal Plant near the roots first. Go to the top of the root and look for the little canister that looks like an Air Bladder. Interact with Tziporah “ZIP” Malk’s message, and this should give you the Kurul Level Access Key, which is the one needed to open the door in the Tadpole Pens.

You can explore around the cave system here in the Blackbox Zip area first, so you can make your run efficient. There’s a lot of Lithium here, which will probably be the first time you’ll encounter this rare material.

After exploring the caves, you can go back to the Tadpole Pens, and you can open the door. There are a lot of scannable objects inside, including the Power Storage. Continue through the rooms until you find the ladder that takes you to the Noa Terminal. There’s also breathable oxygen in the room here, so you don’t have to go back to the oxygen blooms if you need them.

Interact with the terminal and continue through the lore. It should also finish the Investigating the Tadpole Pens mission and lead you to the next chapter, Aliens.

This whole section should still be doable without a vehicle and a Rebreather, which is how I did it, but it isn’t worth the trouble.