Key takeaways
- The Underdark is a region, not one settlement Its named areas include Ebonlake Grotto, Decrepit Village, Dread Hollow, the Arcane Tower, Selûnite Outpost, Storehouse, Grymforge and the Festering Cove.
- There are four practical entrances from the surface the Defiled Temple, the Zhentarim Hideout, the Overgrown Tunnel’s mushroom circle and the Whispering Depths.
- The Myconid Colony is the safest social hub It contains merchants, quest-givers, healing opportunities through dialogue and several important story branches.
- Grymforge is part of the Underdark’s Act One progression, but it is a larger and more dangerous subarea. It contains Nere, the duergar and deep gnome conflict, the Adamantine Forge and the elevator to the Shadow-Cursed Lands.
- Many of the best rewards are easy to miss These include Phalar Aluve, the ingredients for Mourning Frost, the Sussur materials, Luminous Armour, the Club of Hill Giant Strength and several character-specific quest rewards.
- The region has few conventional services Blurg, Derryth Bonecloak and Omeluum provide the principal merchant functions, while the myconid colony serves as the closest equivalent to a safe settlement.
About this guide
Scope: Baldur’s Gate 3, base game, Act One Spoiler level: Major Act One spoilers, including Grymforge, the Adamantine Forge, BOOOAL, the Spectator and several companion or quest outcomes.
Overview
The Underdark is a major Act One region in Baldur’s Gate 3, not merely the area around the Myconid Colony. It is a broad network of caverns, lakeshores, ruins, abandoned settlements and dangerous tunnels beneath the surface. The explorable section in the game is only a small portion of the wider Forgotten Realms Underdark, but it contains several distinct environments and one of the most concentrated collections of Act One quests, rare equipment, alchemical ingredients and story decisions.
The region is inhabited or contested by myconids, duergar, deep gnomes, drow, kuo-toa, monsters and the remnants of older Selûnite and Sharran projects. It is also the principal alternative route to the Shadow-Cursed Lands, although entering Grymforge does not force you to leave Act One immediately.
Ebonlake Grotto
Ebonlake Grotto, also referred to by the Waypoint name Myconid Colony, is the principal peaceful settlement in the Underdark. It is home to myconids led by Sovereign Spaw. The colony occupies a set of mushroom-lined caverns and paths, with spore clouds, animated corpses and deep rothé nearby.
The colony is the best place to organise your Underdark visit. It contains multiple named NPCs, two merchant characters and several quest branches. It also acts as the centre of the conflict between Spaw and the duergar.
Named entries: Ebonlake Grotto
Sovereign Glut can accompany the party temporarily after the duergar conflict develops. His spore servant ability can raise certain corpses, making the nearby monster encounters much easier. His presence also creates a separate political outcome within the colony.
Named entries: Ebonlake Grotto
Decrepit Village
The Decrepit Village sits beside the Ebonlake and is the central transport point for the Grymforge route. It is a partially ruined settlement with raised wooden structures above a beach and docks below. Rope nets and vertical paths connect the two levels.
When the party first approaches, a duergar group led by Gekh Coal may ambush them. The encounter can be handled through dialogue, deception or combat. Gekh and his followers are searching for Thulla and a missing deep gnome. The party can also become involved in the search for Murk and the stolen boots, depending on how the associated quest develops.
The skiff at the beach is the normal route to Grymforge. It becomes usable after the party deals with the immediate duergar situation, although the exact dialogue and quest state depend on whether the party helps, deceives or attacks the duergar.
Named entries: Decrepit Village
The village also contains evidence of the deep gnome presence in the region, including a journal connected with Wulbren Bongle.
Named entries: Decrepit Village
Dread Hollow and the Sussur Tree
Dread Hollow is a cavern dominated by the enormous Sussur Tree. It is also the site of the Bibberbang area, the mushroom picker encounter and the hostile drow wizard Filro.
The Sussur Tree is important for the quest and crafting chain connected with the Sussur Bark. A Sussur Bark can be used to complete the masterwork weapon project in the Blighted Village. Sussur Blooms are also useful in the Arcane Tower because their anti-magic properties can disable Arcane Turrets and interact with the tower’s machinery.
The Bibberbang cave is hazardous because the mushrooms can explode when disturbed. The safest approach is to avoid unnecessary movement through the cluster, use ranged attacks or movement abilities where appropriate and rescue the trapped mushroom picker without triggering a chain reaction.
Named entries: Dread Hollow
Baelen Bonecloak is trapped among Bibberbang mushrooms. The encounter can reward the party with access to Noblestalk, but the outcome depends on how the rescue is handled and whether the mushroom field is detonated.
Named entries: Dread Hollow
Arcane Tower
The Arcane Tower is an abandoned wizard’s tower overlooking the Ebonlake. It belonged to Lenore De Hurst, who has not returned home for many years. The tower is guarded by Arcane Turrets, animated armour and a hostile or conditional construct guardian named Bernard.
The tower is designed as a vertical puzzle location. Its lower areas are difficult to cross safely until the party understands the relationship between Sussur Blooms, the tower’s power system and the Arcane Turrets. Activating the tower’s generator enables access to further floors and changes the behaviour of some of its guardians.
The tower’s guardian can be approached peacefully if the party has read and correctly answers the relevant book clue. Failing the exchange or choosing hostile dialogue can begin combat.
Named entries: Arcane Tower
Torchstalk Gulch
Torchstalk Gulch is an unnamed but important area east of the Arcane Tower. It contains red mushroom clusters, Torchstalk plants, a dead drow and routes to elevated ledges.
Some of its mushrooms are illusory. The area also contains mushroom circles that connect with the surface circle in the Overgrown Tunnel. These circles can become a useful shortcut between the Underdark and the area near Auntie Ethel’s teahouse.
Festering Cove
The Festering Cove is a hidden side area reached by descending near a concealed waterfall and cragged rock. It is home to kuo-toa who worship BOOOAL, a powerful redcap pretending to be a god.
The party can investigate the deception, challenge BOOOAL, support the kuo-toa’s belief or sacrifice a companion. The choice has permanent consequences, so make a save before committing to the dialogue.
The cove contains the Sickle of BOOOAL and Slippery Chain Shirt, as well as buried treasure. It is not a normal town or service area. Its inhabitants are a hidden religious faction encountered only in this mission-style location.
Named entries: Festering Cove
Selûnite Outpost
The Selûnite Outpost is an abandoned fortified settlement in the south-east of the Underdark. It can be reached from the Defiled Temple and serves as one of the main entrances into the region.
The outpost’s walls and banners show that Selûnite followers once attempted to establish a foothold underground. Documents and remains indicate that the effort failed, with hostility from local inhabitants and the difficulty of supplying an underground outpost contributing to its collapse.
Its most important hazard is the functioning Moonlight Artillery. A statue channels energy through a Moonstone and fires radiant blasts near the entrance. The artillery can make the first visit dangerous, especially for a party that rushes through the gate.
The outpost is not a route back into the Goblin Camp unless that route has already been opened from the other side.
Named entries: Selûnite Outpost
Storehouse and Minotaur Hills
The Storehouse is an isolated structure in the north-eastern part of the Underdark. It contains an elevator connecting to the Zhentarim Hideout above. Its surroundings include the Minotaur Hills, rope netting, mushroom platforms and trapped approaches.
Blast Mines can be found near the netting. Destroying the wrong route may damage the netting, but the party can often climb across mushroom caps instead.
The Minotaur Hills are not a fully developed settlement. They are a traversal and combat area containing minotaurs, concealed routes and access to the Underdark’s broader cave network.
Named entries: Storehouse and Minotaur Hills
Grymforge
Grymforge is a major Underdark subarea reached by skiff from the Decrepit Village. It is a former Sharran fortress and industrial complex occupied by duergar, enslaved deep gnomes and the trapped True Soul Nere.
Grymforge is large enough to deserve separate treatment from the ordinary Underdark. It contains:
Named entries: Grymforge
The party can pursue Free True Soul Nere, negotiate with or oppose the duergar, rescue deep gnomes and use the Adamantine Forge. The forge requires ore and moulds, and its guardian, Grym, must be defeated or otherwise dealt with before the equipment can be collected safely.
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Named entries: Grymforge
From the Defiled Temple
The ladder beneath the Goblin Camp’s Defiled Temple leads to the Selûnite Outpost. This is one of the most direct entrances if the party has already explored the goblin stronghold.
The outpost’s artillery makes the arrival dangerous. Use cover, disable or avoid the firing zone and activate the Waypoint when safe.
From the Zhentarim Hideout
The Zhentarim Hideout contains an elevator leading to the Storehouse. This is a convenient route because it avoids the Selûnite artillery and places the party near the north-eastern Underdark.
The elevator route is especially useful if the party has established friendly relations with the Zhentarim or has explored the hideout before entering the Underdark.
From the Overgrown Tunnel
A mushroom circle in the Overgrown Tunnel connects to the Torchstalk Gulch network. This route is useful for returning to the surface, though it requires the party to discover and activate the relevant circles.
Through the Whispering Depths
The chasm in the Whispering Depths can be crossed with Feather Fall. Without protection, the fall kills the party. With the spell or equivalent effect, the party lands in the Minotaur Hills.
This is a fast but risky entry because the party can arrive close to hostile minotaurs without having established a safe route.
From the Decrepit Village to Grymforge
The duergar skiff is the intended route to Grymforge. The party must deal with the local duergar situation before using it normally. Depending on the quest state, this may involve helping Gekh Coal, recovering the stolen boots, fighting the duergar or using deception.
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Myconids
The myconids occupy Ebonlake Grotto under Sovereign Spaw. Their society is communal and telepathic, but it is not harmless. Spaw expects the party to help deal with the duergar threat, while Glut offers an alternative leadership path after suffering the loss of his own colony.
The central political choice is whether to preserve Spaw’s leadership or assist Glut. This affects available dialogue, combat and rewards.
Duergar
The duergar operate around Decrepit Village and Grymforge. Their immediate concerns include the missing gnome, stolen boots, the deep gnome prisoners and Nere’s excavation.
Some duergar can be negotiated with or manipulated. Others are committed to slavery and violence. The party’s decisions in Decrepit Village affect later Grymforge encounters.
Deep gnomes
The deep gnomes are victims of duergar enslavement. Their storyline begins in the Underdark and develops substantially in Grymforge. Thulla, Barcus Wroot, Wulbren Bongle and Philomeen are associated with this wider thread, though not all remain in the same subarea.
Drow remnants
Drow are present mostly as corpses, petrified explorers and historical traces rather than as a functioning settlement. Dhourn, Filro and Xargrim provide fragments of the region’s drow history. The petrified drow encounter near the Selûnite area is also connected with the Adamantine Forge investigation.
Kuo-toa
The kuo-toa in the Festering Cove worship BOOOAL. Their society is mission-specific and isolated from the rest of the Underdark. Their belief gives BOOOAL power, making the encounter more dangerous than an ordinary redcap confrontation.
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Bulette
A single Bulette roams the Underdark as an unpredictable apex predator. It burrows underground and can erupt beneath the party, making open exploration dangerous. It may also attack other monstrosities, which can sometimes create opportunities for the party to observe or exploit its behaviour.
The bulette drops Bloodguzzler Garb. Its burrowing means that the encounter may occur away from the point where it first appeared, so do not assume that one sighting marks the end of the threat.
Spectator
The Spectator appears near the petrified drow. It can revive or manipulate the petrified drow during the battle, producing a chaotic multi-target encounter.
Use the surrounding terrain carefully and consider speaking with the drow afterwards. Dhourn may provide information related to the Adamantine Forge, depending on whether he survives.
Minotaurs
Minotaurs guard approaches around the eastern and north-eastern areas. They are particularly dangerous when encountered immediately after using the Whispering Depths route.
Arcane Turrets and Animated Armour
These protect the Arcane Tower. Sussur Blooms are central to disabling or bypassing the turrets. Bernard and the animated armour become a separate encounter once the tower’s dialogue conditions are mishandled or abandoned.
Hook Horrors and myconid enemies
Hook Horrors occupy routes near Ebonlake Grotto and the Sussur Tree. Mossy, Noxious and Restless Myconids can appear in hostile encounters, especially when the colony’s internal conflict changes the area’s state.
Grym
Grym is the Adamantine Forge guardian. The encounter is tied to the forge’s lava, hammer mechanism and elemental vulnerabilities. The forge’s rewards are among the most important equipment upgrades available during Act One.
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Signature equipment
Phalar Aluve is a particularly valuable early weapon. It can be freed with a DC 15 Strength check or a DC 15 Religion check, with relevant class or deity advantages affecting the latter. Its special abilities can either support nearby allies or debuff nearby enemies.
Signature equipment
| Item | Location | Notes |
|---|---|---|
| Phalar Aluve | Embedded in stone near the central Underdark | Requires a Strength or Religion solution to remove it |
| Mourning Frost | Crafted from Icy Crystal, Icy Helve and Icy Metal | Components come from Filro, Dhourn and Xargrim |
| Club of Hill Giant Strength | Arcane Tower | Obtained by breaking the Stool of Hill Giant Strength |
| Light of Creation | Arcane Tower | Associated with Bernard |
| Luminous Armour | Selûnite Outpost | Found in a hidden area |
| Helmet of Smiting | Selûnite Outpost | Located in a locked chest |
| Bloodguzzler Garb | Bulette | Fixed monster reward |
| Sickle of BOOOAL | Festering Cove | Connected with the BOOOAL encounter |
| Slippery Chain Shirt | Festering Cove | Loot in the kuo-toa area |
| Exterminator’s Axe | Gekh Coal | Loot from the duergar leader |
| Blast Pendant | Dhourn | Loot or acquisition depends on the encounter |
| Skybreaker | Arcane Tower garden | Chest reward |
| Explorer’s Ring | Bibberbang cave | Found on a skeleton |
Crafting and alchemy
Timmask Spores can be collected from triggered mushrooms if the character avoids or survives the associated effect. Nightlight Fronds require a successful Nature check to harvest safely.
The Underdark contains several rare ingredients
Hidden chests
Use a character with strong Perception and keep a shovel available. Buried treasure is easy to miss because it is not always directly beside the main path.
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The region contains buried chests around
Find the Mushroom Picker
This quest concerns Baelen Bonecloak in Dread Hollow. Rescue him from the Bibberbang field, then return to the colony and speak with Derryth. The quest can lead to Noblestalk and changes later dialogue.
Help Omeluum investigate the parasite
Omeluum asks the party to gather ingredients and assist with an experiment. The quest does not cure the tadpole, but it provides information and can lead to useful rewards or purchases.
Defeat the Duergar Intruders
This is the principal route into the Decrepit Village and Grymforge conflict. The party can support the myconids, negotiate with Gekh’s group, recover the stolen boots or attack the duergar.
Find the Missing Boots
This quest begins with the missing deep gnome and the duergar’s demand for the stolen boots. Returning them can provide a more peaceful route to Grymforge, although it does not remove the larger conflict there.
Free True Soul Nere
In Grymforge, Nere is trapped behind rubble while poison gas threatens the chamber. The party must obtain explosives or another way to clear the obstruction, then decide how to respond to Nere and the duergar.
This quest is time-sensitive once initiated. Resting repeatedly after entering the relevant Grymforge state can cause the situation to resolve without the party’s intervention, changing who remains available and which rewards can be obtained.
Find the Nightsong
The Underdark contains clues and quest progress related to the Nightsong, but the Nightsong itself is not resolved in this region. Do not treat every temple or relic in the Underdark as the final destination of that quest.
Reach Moonrise Towers
The Underdark route is one of the two major Act One routes to the Shadow-Cursed Lands. The party can reach the next act through the Grymforge elevator after dealing with the entrance conversation and any requirements associated with the transition.
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Mushroom fields
Timmask, Bibberbang and Torchstalk mushrooms can trigger chain reactions. Avoid jumping blindly through glowing or clustered fungi. Turn-based mode is useful when rescuing Baelen or harvesting ingredients.
Vertical routes
Many Underdark paths are designed around ledges, mushroom platforms and climbable surfaces. Bring Feather Fall, Misty Step, enhanced jump effects or a character capable of safely scouting ahead.
Long rests and time-sensitive states
Some Grymforge events can advance after repeated rests once Nere’s situation has begun. If you enter the area and receive warnings that an event is urgent, investigate before leaving for a long rest.
Moonlight Artillery
The Selûnite Outpost’s artillery is not ordinary decorative scenery. It can deal radiant damage to creatures in its firing area. Approach from cover and use the terrain rather than walking straight through the gate.
Arcane Tower power system
Sussur Blooms are not merely ingredients. They are a practical tool for reaching and powering the Arcane Tower. Keep at least one available when entering the tower’s lower garden.
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This route sees most of the region while reducing backtracking:
An alternative is to visit the Selûnite Outpost early, especially if you entered through the Defiled Temple. In that case, disable or navigate around the Moonlight Artillery before exploring the eastern routes.
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Arcane Tower power system: steps
- 01Enter through the Goblin Camp or Zhentarim Hideout.
- 02Activate the nearest Waypoint.
- 03Visit Ebonlake Grotto and speak with Spaw, Glut, Blurg, Derryth, Omeluum and Thulla.
- 04Explore the Sussur Tree and Dread Hollow.
- 05Rescue Baelen and investigate the Bibberbang area.
- 06Visit the Arcane Tower and collect Sussur materials.
- 07Find Phalar Aluve in the central Underdark.
- 08Explore the Decrepit Village and resolve the Gekh Coal encounter.
- 09Return to the colony to resolve the duergar and Glut branches.
- 10Take the skiff to Grymforge.
- 11Explore Grymforge before triggering or resting through Nere’s crisis.
- 12Complete the Adamantine Forge if you have the required materials.
- 13Use the elevator to the Shadow-Cursed Lands only after finishing the Act One Underdark content you want.
Is Grymforge part of the Underdark?
Yes. In Baldur’s Gate 3, Grymforge is a major named location within the Underdark region, although it is large enough to function as a distinct subarea with its own map, factions, quests and Waypoints.
Is the Myconid Colony the whole Underdark?
No. It is only one settlement within the region. The Underdark also includes the Arcane Tower, Decrepit Village, Dread Hollow, Festering Cove, Selûnite Outpost, Storehouse and Grymforge, as well as several unnamed exploration areas.
Can I enter from the Whispering Depths?
Yes, but you need Feather Fall or an equivalent way to survive the descent. The party arrives near the Minotaur Hills and may immediately face danger.
Does the Underdark permanently lock me out of the surface?
Not immediately. The party can generally travel between Act One areas while progression remains available, but certain story states, long rests and transitions to later acts can change or resolve quests. Treat Grymforge’s Nere sequence and the move to the Shadow-Cursed Lands as progression points.
What is the best item to prioritise?
Phalar Aluve is one of the most accessible high-value rewards because it can support the whole party and remains useful well beyond the Underdark. If your build benefits from cold damage, completing Mourning Frost is another strong priority. The Adamantine Forge can also produce excellent equipment, but its rewards require more preparation and a difficult guardian encounter.
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Sources
- Underdark - bg3.wiki — bg3.wiki
- Decrepit Village - bg3.wiki — bg3.wiki
- Travel through the Underdark - bg3.wiki — bg3.wiki
- Arcane Tower - bg3.wiki — bg3.wiki
- BOOOAL - bg3.wiki — bg3.wiki
- Selûnite Outpost - bg3.wiki — bg3.wiki
- Selûnite Outpost - bg3.wiki — bg3.wiki
- Bulette - bg3.wiki — bg3.wiki
- Phalar Aluve - bg3.wiki — bg3.wiki