Once you have successfully completed the surface section of the game, you can then travel and explore the rather large and dark underground area.
However, you might be wondering how one can actually do this, well let us begin..
This following guide will show you the location to this underground area, alongside how to actually access it too. Keep a note that there is actually 4 possible ways to get there, I’ll show you all 4.
You can start your search by heading to the Putrid Bog section of the map, (x-48, y:266). Please note that this specific place is where the Save Mayrina side quest is. The Teahouse may not be open until that quest is complete.
Then you can track down the actual Gnarled Teahouse, which will have a rather spooky looking entrance way that consists of a rather bleak looking set of stairs and a Skull of some kind arched over the actual doorway, enter this very building though it may look daunting I suppose but hey needs must right? Just ask someone nearby if you can hold their hands or something.
Anyway whilst inside the doom and gloom feel free to inspect the nearby Fireplace, doing so will reveal a hidden staircase behind said Fireplace.
Welcome to the Overgrown Tunnel, again it doesn’t look very pleasant does it?
Heading to coordinates x:-307 y:586 will take you to what seems like a dead end, it actually isn’t.
Here go into your character’s inventory and equip a Whispering Mask that may or may not of automatically placed itself lovingly into your collection. If there isn’t one there however, then do not worry as they should be in plenty of numbers scattered across the actual floor.
After equipping one feel free to examine the root wall with green lights on it, in doing so you will unlock a secret area.
Pass into this secret area, we will need to keep the strange mask though as we will be needing it again in just a minute, so do NOT throw it away or something
You will now want to head to the following coordinates (x:-345 y:563) and use the Jump ability to get past the Waterfall here
Here you will come to a floor full of Gas, we should not need to walk in it so ignore it for now.
Just after passing through the Waterfall do not move anywhere just yet, instead move your camera angle to the left and into a more darkened area that thankfully has no gas in it.
Then using the Misty Step ability you should then be able to teleport into that darkened section.
Remember when I said we can’t throw that strange mask away? Well here is why, whilst in this darkness you will now once again need to equip the mask, do so. If for some reason you no longer have it then you will need to run all of the way back in order to get another and then return here in order to continue.
With the Whispering Mask on once again, examine the barely visible walls in order to be able to access yet another secret area (x:-352 y:582)
After successfully passing through be sure to then once again take the mask off, so we don’t have anyone invading our minds or something. I laugh at Gale’s comment to this ha!
Examine the lovely green puddle nearby, you will now teleport to the Underdark. Congratulations you made it!
The other entrance to the Underdark involves travelling to the Goblin Camp and to the coordinates (x: -105 y: 451) and through the doors here to the Shattered Sanctum
We now want to gain access to the Defiled Temple, which is at the coordinates (x: 402 y: 31)
From there follow the path left and around and into the section with the Moon Puzzle
In this very same room there will be a bench nearby, above this bench there should be a lever, use the lockpicking ability in order to open the nearby door
If you head through the now open doors, you should reach Selunite Outpost.
Now head to the obvious locked gate, to the right of it you should be able to find a lever, use it. The gate will now open and you will have arrived in the Underdark.
(NOTE: This is probably the most difficult route of getting to the Underdark, as it contains a lot of deadly enemies that can cause problems if you are not prepared. Alongside this, there will be a lot of jumping involved too)
Anyway for this possible route we want to be at Blighted Village and the coordinates (x: 28 y: 400)
Then inspect the nearby Well to then find yourself in Whispering Depths, head left at the first folk and then right at the next one, then follow the next path North and through a huge chunk of web which will be located to the left
After that climb the nearby Cragged Rock down, then head in a more North West direction.
When you arrive at the coordinates (x: -555 y: -365) and to the area in the above map, you will now need to use the Feather Fall ability.
Then using the Jump ability look down to the rather dark abyss below you, you need to jump down there so position yourself correctly and take a leap of faith.
If you managed to do all of this correctly, then your character will mention that people must of fallen as they are now surrounded by broken bones, most importantly now though is that you are now officially in the Underdark.
From there keep jumping down various holes, there is really only one way until you are finally at a proper area of the Underdark. Be warned though, when you have jumped through the next hole in the ground you will instantly be confronted by giant Minotaur enemies, but hey you made it to your destination, right?
For this final possible route to the dark Underdark abyss, you will now want to be at the Ebonlake Grotto and to the coordinates (x: -64 y: 587), this area is where you can actually start both the Duke and Trapped Man side quests
Okay whilst in the Grotto, head to the section in the North West of the Water Fountain. This is where you may of found the ring during the Trapped Man side quest. We will be taking the Zhentarim Hideout route.
Now just beyond the barn is another building with a Shabby Door. Gain access to this shabby door and then once inside look for a hatch on the floor
Then head to lower ground and to the hidden stairs in the North West corner of the room.
Head through the Iron Gate. Then here you should see some wandering npc, ignore them for now and climb on up the next set of wooden ladders
Once up top, choose the middle path in the next fork. Then head down the next set of ladders here to the right
Head across the wooden bridge and here you should notice the poor and lonely looking Karad
Now what you want to do here is, switch to crouching and pickpocket the Mechanical Key from him
With the Mechanical Key now in hand, turn around towards the pet Owlbear animal and crouch your way through the wall next to it.
Use the newly acquired key on the Elevator Winch. You should now be in the Storehouse
The Storehouse will lead you to the Underdark.
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