In this guide, you will learn how to find the Sea Emperor and Primary Containment Facility in Subnautica.
Starting from the coral tube sticking up out of the water, you will need to head about one bump to the right northeast until you reach a large drop with a large cave entrance in the bulb zone.
It is recommended to have cyclops with an Mk3 depth module and sonar or a prawn suit with an Mk2 depth module, a grapple arm, an ultra or high capacity O2 Tank, and a sea glide, and a reinforced dive suit.
The main threats you will encounter are the sea dragon leviathan, you have to avoid them, and the lava lizard, you can either avoid or kill using the knife and stasis rifle. You will also encounter the warper, which can warp you out of your vehicle unless you are in the cyclops. You can either run from it or damage enough until it warps away.
There is also lava larva in the lava zone that latch on to your cyclops and drain energy from it, so you can either get the thermal reactor for the cyclops. Or you can bring extra power cells and take out power cells when you aren’t in your cyclops while in the lava zone.
The coordinates for this location are (200, -1440, -222).
You will need to open two doors to get to the sea emperor. You will need to have two blue tablets for those doors, so make sure you have them before going to the facility.
Here is the drop and entrances your looking for:
Once you reach the entrance, you will need to continue through the entrance and eventually reach the lost river. You have to look for a large hole that will lead to the inactive lava zone.
There is also a good chance that there will be a ghost leviathan swimming around/above the large hole you are looking at. So you have to avoid it and get down the hole as quickly as possible.
It is the large hole your looking for.
Once you’ve reached a large area that looks like this, you will see the lava castle straight ahead. You have to head left of the lava castle and look on the seafloor for a large opening/hole, go down into it, and it will lead you to the lava lakes/active lava zone.