'Investigate the Tadpole Pens' walkthrough in Subnautica 2

[Ed. note: Before you dive in, be sure to open the character menu and enable all landmark signals. This will make it easier to spot the locations mentioned in this guide.]

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How to investigate the Tadpole Pens in Subnautica 2

Shortly after finding the Wander Blackbox and curing the Angel Comb, you should get a Noetic Advisor alert named "tadpole pens." Listen to the alert to start the "Investigate the Tadpole Pens" mission. Before you head out, it's highly recommended to bring food, water, a few distraction flares, a fully charged scanner, and an air bladder. As this mission takes you deeper than ever before, there's a greater risk of drowning, so the air bladder's emergency oxygen can be a lifesaver. You must have equipped a basic air tank, but you don't need an advanced air tank or submarine for this mission.

Starting from the Lifepod, swim 690 meters east. You do not need to dive down until you're right above the signal. In the picture below (left side), you see the Tadpole Pens building in the distance, but be sure to aim for the oxygen tunic, the small blue plant that emits bubbles of oxygen, in the gorge opposite the building's entrance.

Touch the blue bubbles to replenish your oxygen, then enter the Tadpole Pens and head left to press the red button in the corridor.

Unfortunately, the door won't open as you need a keycode. Head back to the oxygen tunic outside before your oxygen runs out.

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How to get the Tadpole Pens keycode in Subnautica 2

Feel free to explore the Tadpole Pens and start scanning, but know that the keycode isn't among the loot. A few minutes after pressing the red button, you will get another Noetic Advisor alert, which reveals the location of the Zip Blackbox. Interacting with this blackbox will get you the access key you need.

It's recommended to return to the Noetic Advisor (the nearest one available, which is probably the one in your Lifepod at this point) to listen to the message and obtain the Zip Blackbox signal, but if you don't want to swim all the way back, you can still follow this guide without it.

If you start from the Tadpole Pens, swim 210 meters to the southwest. Be sure to replenish your oxygen at the oxygen tunics along the path. See the circular alien device on the cliff's edge? Swim down, and pass through the large gap on the left (the one closest to the volcanic mound with the jellyfish ring). From there, take the tunnel to the southwest, leading into a large cavern with a large, fiery coral in the center.

If you start from the Lifepod, swim 350 meters southeast, passing Chap's Blackbox. At the edge of the cliff, swim down, use the oxygen tunic, then go down the large hole next to it. Feel free to explore the Hot Cave Basement at the bottom before moving on.

When you're ready, continue north-northeast and take the first tunnel on your right, leading into a large cavern with a large, fiery coral in the center.

No matter which route you took to get here, rest up at the oxygen tunic on the north-northeast side of this room. See the cave opening next to it? Swim all the way down to the bottom of this cave to find Zip's Blackbox. It's on the large purple root. Doing so will grant you the kurul level access key.

Now, return to the Tadpole Pens and press the red button again to complete the "Investigate the Tadpole Pens" mission in Subnautica 2. There's a room with breathable air and a Noetic Advisor behind the previously closed doorway.