Sons of the Forest: How To Open The Arm Door [Step By Step]

Whether you get scared or not, be brave enough to venture through the horrors to open the arm door located within!

Sons of The Forest is probably one of the most interesting games where players are made to pass through caves, solve puzzles, craft items, go traverse the lands to ge their hands on precious loot that can help them further progress in the game. Similarly to that, players might have quite a bit of difficulty trying to figure out how to open the Arm Door in Sons Of The Forest since it requires two essential items; maintenance key & golden armor.

Important: To open the arm door and complete one of the final missions in the game, players need to get the maintenance key and wear golden armor. 

Key Takeaways

To open the arm door, follow these steps:

  1. Locate the arm door deep within an underground building on the opposite end of the island.
  2. Note that the arm door is also referred to as the Golden Hand Seal Door.
  3. Ensure you have two essential items: the golden armor and a maintenance key.
  4. Wear the golden armor suit, which can be found in a cave inside the level 2 building on top of a couch in the living room.
  5. Align your character’s arm with the marking on the arm door to open it.
  6. The golden armor suit provides full HP and protection during combat.
  7. Obtain the maintenance key from a bunker underground; it’s located on a table beside a 3D printer.
  8. The maintenance key can also be used to access the katana in the game.

Follow these steps to successfully open the arm door in the game.

How To Locate Arm Door 

First things first, one thing that players should know is that whenever they are playing the game, the Sons Of The Forest Arm Door is also referred to as the golden hand seal door; therefore, players should know not to confuse the two terms. 

  1. Make sure you have the golden armor suit and the maintenance key; you’ll need both to unlock the door.
    Way To Enter The Arm Door
    Way To Enter The Arm Door (Image Credits Exputer)
  2. Head to the opposite side of the island, guided by your GPS.
  3. Look for an entrance covered by nature, with a dead worker in a red suit leaning to the right of it.
    Nature Overtaken Entrance
    Nature Overtaken Entrance (Image Credits Exputer)
  4. Follow the green beacon on the opposite end of the island, navigating around snowy mountains.
  5. Approach the locked door and use the maintenance key to open it.
    Maintenance Key Entrance
    Maintenance Key Entrance (Image Credits Exputer)
  6. Inside the building, proceed straight and pass through three doors.
    One Of The Three Doors
    One Of The Three Doors (Image Credits Exputer)
  7. Keep going until you reach a yellow door, then turn left and exit the room.
    Yellow Door
    Yellow Door (Image Credits Exputer)
  8. Continue through the hallway, passing a wet floor sign, and head toward the lobby.
  9. Enter the penthouse, then go into a room with a black ottoman.
    Black Ottoman
    Black Ottoman (Image Credits Exputer)
  10. Enter the dismantled bathroom and continue into the cave.
  11. When you encounter a lined door, you’ve found the Sons of the Forest Arm Door, also known as the golden hand seal door.

How To Open Arm Door 

Lined Door
Lined Door (Image Credits Exputer)

Whenever you do encounter the door, players need to open it to go inside. 

  • The way that players can open the door is by getting close to it and interacting with it by pressing E, 
  • Players need to be wearing the golden suit whenever they approach the armed door. Otherwise, they aren’t able to unlock it. 
How To Open Arm Door
How To Open Arm Door (Image Credits Exputer)
  • All players need to do is use their arm, align it with the arm marking on the door, and slam their arm against it which ends up opening the door for them. 

Gold Armor Suit Location  

Moving on, now that players know how to locate and open the arm door in Sons of The Forest, the next thing that we will be taking a look at is how to locate the gold armor suit, which is a key essential to open the door. 

  1. Head to the opposite end of the island by following the map, climbing mountains, and navigating through snowy terrain.
    Opposite End Of Island
    Opposite End Of Island (Image Credits Exputer)
  2. Look for a green beacon that leads to a well-hidden cave nestled between tall mountain edges and two cliffs with a large cut in the middle for cave access.
  3. Enter the cave and start descending. Use your flashlight as it’s very dark.
    Entrance To Cave
    Entrance To Cave (Image Credits Exputer)
  4. Navigate through narrow passageways and eventually turn right from a cliff drop to find a massive hole in the ground.
    Using Torch
    Using Torch (Image Credits Exputer)
  5. Jump into the hole to enter a building.
    Hole In The Ground
    Hole In The Ground (Image Credits Exputer)
  6. Proceed down the hallways and use the maintenance key (explained later) to open a door by holding “E” when prompted.
  7. After opening the door, turn right from the dead body in front of you, and continue until you reach a locked yellow door.
    Locked Yellow Door
    Locked Yellow Door (Image Credits Exputer)
  8. Open the yellow door, watch the cutscene, and continue through the corridor.
    Running Through The Corridor
    Running Through The Corridor (Image Credits Exputer)
  9. Be cautious, as there are numerous enemies ready to attack you; stay alert.
  10. Continue through the corridor until you find teal-illuminated hallways that resemble backrooms. Locate a level 2 door.
    Level 2 Door
    Level 2 Door (Image Credits Exputer)
  11. Enter the level 2 door, run past a dead body in the room, and turn right from the second room with a door leading further in.
  12. Inside the hallway with white illuminated walls, you’ll find yourself in an apartment.
    White Illuminated Walls
    White Illuminated Walls (Image Credits Exputer)
  13. In the living room, on the couch, you’ll discover the Golden Armor Suit.
    Golden Armor On Couch
    Golden Armor On Couch (Image Credits Exputer)

Why Do You Need Golden Armor?

Lastly, let’s take a quick look at the uses of the golden armor. 

  • The golden armor itself is a progression item that players can get their hands on, and once they have it in their arsenal, they don’t need to worry about it being lost or getting broken. 
  • The main use of the golden armor is to grant the player a full HP bar essentially. 
  • It is mostly focused on battles where players use ranged attacks rather than melee-based attacks. 
  • The armor is also used in the form of a key to open the arm door. 

Maintenance Key Location In Sons Of The Forest

Last but not least, players need the maintenance key to open up the arm door, and the maintenance key is also needed to get the armor suit. 

Right End Of Island
Right End Of Island (Image Credits Exputer)
  • Players need to make their way down towards the bottom right area of the island, a bit to the eastern side of the snowy mountains, and players need to travel around the mountains and then make their way down. 
  • Players need to get their hands on a shovel for this process. 
  • Locate an area where there are yellow leaves on the ground, and the area seems suspiciously well-protected. 
Square Entrance
Square Entrance (Image Credits Exputer)

As soon as you start digging into the ground, a square entrance pops up, which leads deeper inside the ground. 

  • Interact with it by clicking or holding E, and as you head down the ladder, you are met with a mildly illuminated room. 
Going Through The Corridor
Going Through The Corridor (Image Credits Exputer)
  • Start making your way down the long corridor until you encounter a door on your right. 
Furnished Apartment
Furnished Apartment (Image Credits Exputer)
  • As you head inside the door, you are met with a perfectly furnished apartment and a table on the far end of the room with a 3D printer on it. 
Interacting With Key
Interacting With Key (Image Credits Exputer)
  • Towards the right side of the table, the maintenance key is located, and players can pick it up by interacting with it. You can also pick up an album cover which is present right next to the tv. 
Maintenance Key Obtained
Maintenance Key Obtained (Image Credits Exputer)

The maintenance key can be used to get your hands on the Katana as well. 


And there we have it! All that players need to know about the Sons Of The Forest Arm Door, and with that, we will wrap up our guide! While we’re here, why not read up on our Sons Of The Forest How To Make Rope guide which goes in detail about how you can make a rope! If you’ve wanted to know a solid source of water in the game, then our Sons Of The Forest Get Water Collector guide will tell you all there is to know!

Apart from this, you might also really like our Sons Of The Forest Quick Select guide since it goes in depth about the uses of the quick-select in-game. 

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Mina is a Senior Guides Writer and a fanatic who’s obsessed with playing games and writing about them. She’s invested more than 2,500 hours in games like Genshin Impact and Honkai Star Rail. With a Bachelor’s Degree in Journalism, she loves to write detailed guides for beginners and pros in the Gacha Games world. You can follow Mina's gaming activity on her Steam and PSN Profiles.

Experience: 3+ Years

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