This guide tells you how to open all the doors in the Atomfall Chemical Testing Bunker, open the vault, and retrieve the Corrupted Dagger on Midsummer Isle, along with some Training Stimulants, some ammo, and a bunch of crafting materials.
How to Solve the Atomfall Chemical Testing Bunker Door Puzzle
The Atomfall Chemical Testing Bunker door puzzle requires you to go to certain rooms in a specific order and unlock them one by one. However, attempting to explore this bunker at the DLC location Midsummer Isle can be tricky if you're not adequately prepared.
Preparing to Explore the Chemical Testing Bunker
The Chemical Testing Bunker has its fair share of hazards and you'll want to make sure you have the right equipment before going further.
As this location is on Midsummer Isle, you'll also need to travel there by way of Wyndham Village. You can speak to Bill Anderson on the dock and he'll take you to Midsummer Isle, but you should prepare yourself before you depart.
You'll have to face Druids, Bandits, Ferals, Thralls, and a few new enemies such as an Aquatic Feral variant and Crow Swarms. (Yes, crow swarms.) You'll want to ensure that you have adequate ammunition for all of your weapons; it may be a good idea to visit all of the merchants in the main areas of the map and stock up on ammo before departing.
The Poison and Infection debuffs are present in many locations, so you'll want to be sure that you can craft the requisite cures for those items. Finally, you'll want to have access to the Signal Redirector tool as you'll need it to get all of the loot in the Chemical Testing Bunker.
Once you're ready to go, speak with Bill Anderson on the Wyndham Village docks and make your way to Midsummer Isle.
Where to Find the Chemical Testing Bunker
The Chemical Testing Bunker can be found on the northern part of Midsummer Isle.
You'll likely encounter several Bandits and Druids along the way. You can sneak past them, outrun them, or fight them.
Note that there is a merchant at 32.2E, 97.9N and another one at 33.9E, 102.3N. Both of these merchants are on the way to the Chemical Testing Bunker, so you may as well drop in and see what they have in stock.
Entering the Chemical Testing Bunker
Once you get to the Chemical Testing Bunker, you can enter it from the southern door as shown in this guide's cover image. Alternatively, you can approach it from the east.
Take note that the doors of the Chemical Testing Bunker are airlocks that remain closed once you pass through; make sure to enter and exit through the same door where possible or you could get locked out of one of the doors.
For example, if you enter through the southern door, exit through the east door, and return to the southern door from the outside, you will find that the southern door's airlock is completely inaccessible from the outside.
Clearing the Halls
Once you're inside the Chemical Testing Bunker, it's a good idea to go through all of the hallways. There are quite a few Thralls to be found here, and it's a good idea to kill them now before you open up the side rooms and you have to face even more.
If you haven't killed Thralls before, it's best to hang back and slowly hit them with repeated headshots. (Alternatively, you can use melee if you feel you're skilled enough with it). Thralls always move at a slow, deliberate walk, so it's quite easy to outrun them if need be.
Restoring Power
Next, we'll want to bring power back online in the facility. This is done via the Power Control Room. Make a left from the "A" entrance (or follow the signs on the wall) and you'll find the room with a locked door. A vent giving you access to the room can be found around the corner.
There is poison gas in this room, so you may want to consume an Antidote before going forward.
You'll also find that someone has already taken up residence in the room: a Thrall is waiting for you inside.
You have just enough room to maneuver in there if you decide to crawl through the vent. Alternatively, you can throw grenades through the vent. Using grenades for one Thrall is kind of a waste, though, as they're very tanky; it's better to confront them and kill them with headshots or melee.
Either way, kill the Thrall and activate the button in this room. It will activate several exhaust fans throughout the facility and remove some of the poisonous gas, making it a little easier to move around.
Entering Administration
Our next step will be to head to the Administration room. This room has at least 5 Thralls inside, so you'll want to make sure you're fully healed up before you even attempt heading into here. Return back to the Pneumatic Tube at either entrance to resupply if need be.
Head into Research Lab B and kill any Thralls you find inside this room. There is some poisonous gas in these rooms, but there are plenty of safe areas where you can stand away from it, so you can avoid consuming an Antidote for now.
Make two right turns from the entrance to Research Lab B and you'll find a vent on the southern wall.
When you go through this vent, you'll be in Administration. However, this room is full of Thralls, so you'll need to move quickly.
Head straight and make a right to find a barred door.
If you're quick, you can make it to the door, open it, and run out into the hall before any Thralls get close enough to hurt you.
Turn around and you'll likely find at least a few of the Thralls following you.
Turn around and kill all of the Thralls. You can kite them through the halls pretty easily; take your time and avoid making any mistakes.
Next, head back into Administration. You'll find a total of 2 or more Training Stimulants in two separate locations on desks.
Where to Find the Advanced Research Keycard
While you're in Administration, you'll also want to look for a metal briefcase with two red stripes sitting on a desk. This case contains the Advanced Research Keycard.
Loot the Advanced Research Keycard, then head back out into the hall.
Looting Research Lab A | How to Open the Cold Storage Door
Next, you should loot Research Lab A. To get there, head back into Research Lab B. Make a left from the entrance and you'll find a vent on the western wall.
This vent will take you into Research Lab A. A single Thrall can be found inside, so make sure you're ready for a fight.
When the Thrall is dead, head up to the door marked "Cold Storage" with an electronic lock. Take out your Signal Redirector and look up and to the left of the lock to find the box you need to trigger to power up the lock.
You'll find a B.A.R.D. Crate with at least 1 Training Stimulant inside here, along with some other crafting materials.
Head back out into the hall and make your way to Advanced Research.
Clearing Advanced Research
The door to Advanced Research is jammed open, so you'll have to squeeze through. There is a single turret to your right; be ready to destroy it with a gun as soon as you enter.
A total of 3 Ferals can be found in this room, one of which is just outside the Vault. Carefully look at the glowing fungus to find them. You can kill each of them with a single thrown Molotov Cocktail apiece if you have any on hand.
Head to the right side of the room and you'll find a box that you can trigger with the Signal Redirector. Activate it, and you'll clear the gas out of this room.
Once the gas is cleared and the 3 Ferals are dead, you can safely head down to the Vault.
How to Open the Advanced Research Vault in the Chemical Testing Bunker and Get the Corrupted Dagger
You can open the Advanced Research Vault in the Atomfall Chemical Testing Bunker by using the Advanced Research Keycard found in the Administration area.
Simply walk up to the Card Reader and interact with it. You'll open up the Vault and get access to the ultimate treasure of this location: a unique knife.
The Corrupted Dagger is a small melee weapon with the following stats:
- Low Damage
- Fast Attack Speed
- Increased Damage to Infected Enemies
This makes it an ideal melee weapon for taking on Ferals, Thralls, and infected Druids throughout the world.
Once you have the Corrupted Dagger, thoroughly loot the room as you can find a lot of crafting materials here. If you run out of storage space, you can unload some of your stuff at the Pneumatic Tubes near either entrance.
Exiting the Bunker
With the Corrupted Dagger in hand, you've now acquired the ultimate treasure of the Atomfall Chemical Testing Bunker. There are plenty of crafting materials and a few Training Stimulants to be found throughout the facility, so make sure you grab everything you can.
When you're done, you can exit the facility and go back to exploring Midsummer Isle.
We're at the end of our guide on the Atomfall Chemical Testing Bunker, but there's plenty more to explore — check out our other guides below!
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