Unlocking the Door in Subnautica 2’s Tadpole Pens: A Quick Guide

Figuring out how to explore the Tadpole Pens in Subnautica 2 is your first real puzzle in the game. You’ll need to dive into the Hot Caves to find the door code that grants you access. It seems that NOA won’t direct you to the Tadpole Pens until you’ve collected the other black boxes—at least that was my experience.

This journey is significantly longer than retrieving any of the previous black boxes, so make sure to stock up on essentials like water, food, batteries, health kits, and maybe a distraction flare just in case. Here’s how to reach the Tadpole Pens and locate the Zip black box to unlock the door inside.

Once you receive the quest to visit the Tadpole Pens from NOA, you’ll get a signal for “Investigate Tadpole Pens,” which is about 675 meters east of the Lifepod in the lava vents area. To get there, you’ll need to unlock the Heat Tolerance Adaptation by clearing the Angel Comb located 200 meters northwest of the Lifepod, at a bearing of 300 degrees on the compass.

For this, you’ll require the Sonic Resonator tool to destroy the viral flowers in the area, allowing you to claim the Adaptation just like you did for the food digestion upgrade. It’s also a good idea to upgrade your O2 tank and craft a Tadpole, along with a Wavemaker to enhance your swimming speed.

Upon reaching the Tadpole Pens, you’ll encounter a door that you can’t unlock. You’ll discover that a colonist named Zip took the door code into the Hot Caves. If you wait long enough, NOA will eventually provide you with the location of Zip’s black box as a mission, but that means making the trek back to your base. Instead, you can use the video above to find Zip’s black box.

If the video isn’t visible, here’s what you need to do:

Once you’ve retrieved the black box, head back to the Tadpole Pens, unlock the door, and enjoy the surprise that awaits you inside.