With so many places to go in Subnautica 2, it’s no surprise that some of those places aren’t totally accessible to start out. Just like in any survival game, you’ll need to do a little searching to find what you need.
As you play through Subnautica 2, you’ll receive some story missions from NOA that send you all over the map. One of those missions will send you to the Tadpole Pens.
These will be fairly dangerous to get to if you aren’t prepared. Thankfully, by the time you’re getting to this point, you should be fairly prepared for this journey.
How to Get to the Tadpole Pens in Subnautica 2

You’ll need the Heat-Resistant Adaptation to be able to survive this area, and having the Tadpole would certainly make it easier. If you don’t, it may be difficult to even make it there.
You’ll also pass by one of the Endurance Biobeds, so stopping may be a good idea. It’ll increase your inventory space in case you find anything else you want to keep on your journey.

Once you reach the facility, you’ll be able to enter through the front entrance. It’ll have the sign next to it and a few other items you can scan around the front.

Turn left, and you’ll see a locked door with a button. You won’t be able to access this until you have the code. Getting this code is a bit of a pain, but when you know where to go, it’s a little easier.
How to Get The Kurul Level Access Key

If you listen carefully to the recordings provided, you’ll hear that the person with the Access Key headed off southwest of the facility – the location of the Zip Blackbox. The best place to start is heading in that direction.

The place that you need to enter is about 200m southwest of the facility. It’s not too far to travel, but if you’re not in your Tadpole, you’ll need to stop off for air every so often.

Look around below you, and you’ll find a ring-like creature surrounding a volcanic vent. Beneath it, there will be a large hole that you can travel down.

Once you head down the hole, there will be an opening to the southwest that you’ll take. This will spit you out in the fire caves that the recording mentions.

The fire caves here can be a fairly tight fit, so you may want to drive carefully, or you can simply get out and swim. That’s not recommended, though, as you’ll burn oxygen pretty quickly.

On the northwest side, there will be an oxygen plant. Turn southwest, and you’ll find a hole that will lead you to your objective.
This is where things start to get dicey. If you’re driving the Tadpole, you can’t bring it all the way down, so park it near the entrance for easy access to oxygen.

At the very bottom of the hole, there is a large crustacean-like arm that will have your objective sitting at the very center of it.

Make your way down there quickly and then hurry back to where you can breathe. Once you’ve grabbed it, you can head back to the Tadpole Pens.

When you arrive, you should be able to get through the door. Take the ladder up to the next level to discover some disturbing truths about the world of this indie game.

