Key takeaways
- The Lower City Sewers are broader than the area around the City Sewers waypoint Explore east, west and north before assuming you have seen everything.
- Do not automatically include the Guildhall, Abandoned Cistern or Undercity Ruins in the location itself. They are connected sublocations with their own pages, encounters and progression.
- The sewage raft is the central transport link It connects the eastern tunnels with Aelis’s area and the route towards Cazador’s Dungeon.
- Several encounters are state-dependent Orin, Voss, Gandrel and the vampire-related material only appear if earlier choices or quest states allow them.
- The most significant fixed rewards are Chancer’s Carcanet, Aelis’s unique loot and the Silver Sword of the Astral Plane if Voss has not already given it to you.
- The area is hazardous rather than conventionally combat-heavy Grease, oil, noxious fumes, tripwires and explosive fire interactions are more important than ordinary sewer monsters.
About this guide
Base game, Act Three. Major spoilers for Baldur’s Gate 3, including companion quests, Orin, Cazador and the endgame.
Overview
The Lower City Sewers are the main underground drainage network beneath Baldur’s Gate in Act Three. They are not a single compact dungeon, nor are they synonymous with every sewer-like area beneath the city. The named location includes the central sewer tunnels, eastern tunnels, sewage-raft route, Aelis Siryasius’s lair and the treasure room beneath Flymm Cargo. The Abandoned Cistern, Guildhall and Undercity Ruins are adjacent, separately named locations, although the player commonly moves between them without obvious visual boundaries.
The sewers are one of Act Three’s most important junctions. They provide routes into the Undercity, the Guildhall, Cazador’s Dungeon and the Abandoned Cistern, while also hosting encounters involving Orin, Kith’rak Voss, Arabella, Gandrel, Aelis Siryasius and Sarin. They are also a useful alternative way to travel around the Lower City when surface routes are inconvenient or unavailable.
Location boundaries and hierarchy
The Lower City Sewers are part of the Undercity, the extensive subterranean region beneath Baldur’s Gate. Their eastern side is reached from several points in the Lower City, while the central tunnels open towards the Abandoned Cistern in the west and the Undercity Ruins in the north. The Guildhall lies to the south and has its own location identity despite sharing the same damp, sewer-like visual language.
For practical exploration, treat the area as four principal internal sections:
Eastern Tunnels
The eastern tunnels contain the main surface entrances, Bhaalist activity, refugees, traps and the route towards the central waypoint. They are the best starting point for players entering from the Lower City or the Knights of the Shield Hideout.
Sewage Raft
The raft line is a transport route running between three piers. It provides access to the eastern tunnels, Aelis’s central section and the sealed approach to Cazador’s Dungeon. The raft starts at the middle pier, and levers call it towards the selected pier.
Mad Sorcerer’s Lair
This is the central area controlled by Aelis Siryasius. It is covered in grease, occupied by grease-based creatures and associated with Sarin’s funeral. The area can be crossed through dialogue, but returning later can still make Aelis hostile.
Treasure Room
The treasure room lies beneath Flymm Cargo. It contains Dairow Vin, the kobold treasure-map encounter and the pipe leading west towards the Abandoned Cistern.
Separate connected areas
The following should be treated as neighbouring locations rather than ordinary rooms in the Lower City Sewers:
The location transition into the Undercity Ruins occurs north of Aelis’s area, near the second waypoint.
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Access and entrances
The sewers have an unusually large number of entrances. Most connect to the Lower City, while others are reached from buildings or adjacent dungeons.
Surface and indoor entrances
The old iron grate in the basement of Beehive General Goods was reportedly interactable in earlier versions, but it is not a current entrance. Treat older guides that describe it as outdated.
Recommended entry routes
For a first exploration: use the manhole between Stormshore Tabernacle and Basilisk Gate Barracks. This leads into the eastern tunnels and places you near the main sequence of sewer encounters.
For the Guild and Minsc-related routes: use the Basilisk Gate area or the Knights of the Shield Hideout. The eastern tunnels connect naturally to the Guildhall side and can trigger important Act Three events.
For Aelis and Sarin: enter from the east, unlock or cross the route to the central sewer area, then follow the raft or the main tunnel towards the sorcerer’s lair.
For Cazador’s Dungeon: enter from the Lower City through Flymm Cargo or another eastern route, then follow the sewage-raft line north. The dungeon-side gate must already have been opened before the sewer-side connection becomes useful.
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Surface and indoor entrances
| Name | Details |
|---|---|
| Heapside Prison | descend through the prison’s manhole or pit latrine. |
| Stormshore Tabernacle and Basilisk Gate Barracks | use the manhole in the alley between them. |
| Golbraith’s Cellar | use the manhole outside the cellar. |
| Knights of the Shield Hideout | descend through the hatch in the basement of Elfsong Tavern. |
| Gardener’s Basement | enter through the wooden door marked “Keep Out” and use the ornate hatch. |
| Flymm Cargo | descend through the greasy, smelly climb in the basement. This reaches the treasure room. |
| Guildhall | the headquarters has a locked sewer-facing door and a hidden connection near the Secret Sewer Vault. |
| Cazador’s Dungeon | the Gloomy Descent is one-way from the sewer side until the corresponding crypt gate has been opened from the dungeon. |
| Secret Sewer Vault | a hidden door connects to the sewer hallway, but it must first be opened from the other side. |
Navigation and transport
The City Sewers waypoint
The City Sewers waypoint is near the western end of the eastern tunnels, at approximately X: -98, Y: 779. It is the main fast-travel point for the area.
The Undercity Ruins waypoint
Continue north through the stone archway beyond Aelis’s section. The minimap changes to Undercity Ruins at approximately X: -138, Y: 907, and the Undercity Ruins waypoint becomes available at roughly X: -141, Y: 941. This marks the transition out of the Lower City Sewers proper.
The sewage raft
Levers call the raft to the chosen pier. You can also use careful positioning, hiding or turn-based mode to move through the central area without immediately triggering Aelis’s encounter.
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The sewage raft: The raft moves between three piers
- 01Southern pier: beside the eastern tunnels. The nearby door towards the main sewer section is locked and can be picked with a DC 15 Sleight of Hand check.
- 02Middle pier: near Aelis’s section and the locked door to the mad sorcerer’s lair. The door requires a DC 10 Sleight of Hand check.
- 03Northern pier: at the end of the raft line, beside the Gloomy Descent towards Cazador’s Dungeon.
Eastern Tunnels
The eastern tunnels are the most varied part of the sewers. The prison route reaches an unremarkable cavern with a breach into the drainage system. The Knights of the Shield route leads through a storeroom containing chests, books about mind flayers, a journal concerning Duke Stelmane and a Scroll of Detect Thoughts. The manhole route initially appears to be a dead end, but a wall can be identified and destroyed after a DC 15 Perception check.
A central passage is filled with Noxious Fumes. Four vents produce the fumes, and a lever on the southern wall disables them. The lever can be activated with a ranged attack. A locked Rustic Chest hidden among the fumes contains random wines.
Further west, Bhaal cultists use refugees as target practice. If the party has made a deal with Orin, the cultists are not immediately hostile, allowing the player to join them, ignore the scene or turn against them. If the refugees flee after the cultists are defeated, three tripwires in the next hallway can kill them unless disarmed. Each tripwire requires DC 17 Perception to detect and DC 15 Sleight of Hand to disarm.
Eastern Tunnels checklist
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Arabella’s cave
West of the main waypoint, an improvised bridge leads to a natural cave where Arabella may be found if she survived into Act Three. She is studying a magical stone that has absorbed stories from many lifetimes in the city. A DC 15 Arcana check, or reading Arabella’s thoughts, reveals more about the stone’s nature.
A buried chest near the route to Arabella can be discovered with a DC 15 Survival check. It contains gold, valuables and a random very rare spell scroll. Nearby, a Traveller’s Chest in a greasy and oily area contains alchemical ingredients and a note concerning their illegal provenance.
Arabella’s presence is progression-dependent. She is not a permanent ordinary sewer resident and should be treated as a continuation of her earlier storyline.
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Aelis Siryasius and the Mad Sorcerer’s Lair
Aelis Siryasius is a Draconic Bloodline sorcerer, not a wizard, despite the description used by nearby corpses and notes. He is holding a funeral for Sarin and initially suspects the party of working with the Cult of the Absolute.
You can attempt to calm him through dialogue and ability checks. Success grants safe passage for the moment, but speaking to him again or re-entering the area can still make him hostile. If combat begins, Aelis is supported by grease-based creatures and the terrain itself becomes dangerous.
The fire surface is especially dangerous. Grease can impede movement and can be ignited by fire spells. Grease Mephits can summon Magma Mephits during combat, so prolonged fights may add further enemies. Picking off patrols before confronting Aelis can reduce the number of creatures drawn into the main battle.
Aelis carries the key to the Grated Iron Door. The chest behind it contains the Scorched Book, gems, alchemical ingredients and gold. Aelis can also drop the Cindermoth Cloak and Quarterstaff +2, according to the location’s loot directory.
Sarin’s Funeral
Sarin’s funeral is one of the most distinctive optional activities in the sewers.
Carrying the skull causes a headless ghost to follow the relevant party member. The ghost disappears if the party leaves the sewers for the surface or enters combat. Returning the skull does not automatically make Aelis hostile if he is still alive.
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Sarin’s Funeral
- 01Find Sarin’s headless glowing skeleton in Aelis’s lair.
- 02Travel north towards the Undercity Ruins.
- 03Find Voiceless Penitent Bareki near the passage to the Ancient Lair.
- 04Take Sarin’s Skull from the red-outlined pouch behind him.
- 05Return to Aelis’s lair.
- 06Place the skull in the skeleton’s interactable slot.
- 07Sarin’s ghost appears, bows and rewards the party with Chancer’s Carcanet.
Treasure Room beneath Flymm Cargo
The treasure room is reached from Flymm Cargo through the greasy climb. A large pipe crosses the area and provides the route towards the Abandoned Cistern. The room is surrounded by flowing sewage and contains a small number of story and exploration encounters.
Dairow Vin
Dairow Vin lies unconscious after consuming several Potions of Sleep while grieving the likely death of his husband. His backpack contains:
Dairow is not a normal merchant or service provider. His presence is primarily a small environmental story and a link to the Guild.
Kobold treasure map
A Kobold Thief near the pipe carries a map referring to Bugthimble and hidden tribe treasure. Reading the map adds a cache marker to the minimap. Five surrounding dirt mounds contain trapped, locked chests with different sewer notes. The actual treasure is in the northernmost mound.
The smaller chests contain the sewer notes. The final chest contains gold and random valuables. The traps are more disruptive than lethal, pushing characters away from the chest when triggered.
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Kobold treasure map: The procedure is
- 01Loot the map from the Kobold Thief.
- 02Read it to reveal the cache marker.
- 03Search the five dirt mounds.
- 04Detect the traps with DC 25 Perception.
- 05Disarm them with DC 15 Sleight of Hand.
- 06Pick the individual chests with DC 7 Sleight of Hand.
- 07Open the northernmost mound’s Marked Chest: Dragon with DC 20 Sleight of Hand.
Important encounters and progression states
Orin’s kidnapping scene
If Orin’s kidnapping event has not already begun through a long rest, it may trigger when entering from the Knights of the Shield Hideout or near the Undercity Ruins waypoint. Orin appears disguised as one of the kidnapped companions, reveals the deception and demands that the party kill Gortash in exchange for the victim’s life.
This means that exploring the sewers can advance Rescue Orin’s Victim without the player deliberately seeking Orin. If you want to avoid triggering the scene immediately, consider completing other urgent Act Three conversations first.
Kith’rak Voss and Qudenos
Depending on the state of Help Kith’rak Voss, Voss may wait near the middle sewage-raft pier with Qudenos, disguised as a red Dragonborn. If the party possesses the Orphic Hammer, showing it to Voss can reward the Silver Sword of the Astral Plane, provided the sword was not obtained earlier.
Speaking with Voss updates the quests concerning Prince Orpheus, Lae’zel and Gather Your Allies. Qudenos can be identified as a true dragon with a DC 15 Insight check. Githyanki and Dragonborn characters receive additional dialogue options. If attacked, both attempt to teleport away on their first turn, although they can still be killed during that turn. Voss’s sword can then be looted.
Gandrel, Chessa and Kass
If Gandrel survived Act One and the vampire spawn were freed during Astarion’s storyline or Investigate Cazador’s Palace, Gandrel, Chessa and Kass appear near the City Sewers waypoint. This is a conditional continuation rather than a guaranteed encounter.
Lorna Esthelian
Lorna Esthelian waits at the northern sewage pier for a date who intends to take her to a palace, strongly implying a vampire connection. The party can warn her or allow the conversation to unfold. She eventually leaves and does not remain in the game. Astarion has additional dialogue if present. The surrounding mirrors, silverware and missing-child posters refer to the Gur children taken on Cazador’s orders.
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Factions
Bhaal cultists
Bhaalist cultists occupy the eastern tunnels and use refugees as living targets. Named cultists listed for the location include:
The cultists’ presence links the ordinary sewer network to the wider Bhaal plot and the Undercity Ruins.
The Guild
The Guildhall is adjacent rather than part of the central sewer location. The Guild, led by Nine-Fingers Keene, uses the underground complex as a headquarters, meeting place and centre for illicit commerce. Its struggle with the Stone Lord’s gang and the Zhentarim feeds directly into sewer exploration, but the Guildhall’s own residents and merchants should be researched on that location’s page rather than folded into this directory.
Stone Lord’s gang and the Zhentarim
The Stone Lord’s gang operates from the Abandoned Cistern, a separate connected location. The gang’s conflict with Nine-Fingers and the Zhentarim is one of the main reasons to explore the western sewer connections.
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Enemies and creatures
The verified creature directory for the main Lower City Sewers is:
The creature totals are location-directory counts, not necessarily a promise that every creature remains alive or hostile in every progression state. Aelis’s creatures may be affected by dialogue, stealth and the order in which patrols are attacked.
The area can also contain or be associated with:
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Loot and collectibles
Other fixed or semi-random loot
Several chests use randomised contents, so the exact item quality can vary. Do not treat every random spell scroll or valuable listed in an older guide as a fixed spawn.
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Named rewards
| Name | Details |
|---|---|
| Chancer’s Carcanet | reward from Sarin after returning her skull. |
| Cindermoth Cloak | associated with Aelis Siryasius. |
| Quarterstaff +2 | associated with Aelis Siryasius. |
| Silver Sword of the Astral Plane | potentially awarded by Kith’rak Voss if the Orphic Hammer is shown and the sword was not acquired earlier. |
| Painted Key | found beneath one of the loose stones in the northern room. |
| Sarin’s Skull | needed for Sarin’s funeral. |
Traps and hazards
The refugee tripwires deserve special attention because the party can win the fight against the cultists and still lose the refugees immediately afterwards. Disarm the route before allowing them to flee.
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The main hazards are
| Hazard | Where | Counter |
|---|---|---|
| Noxious Fumes | Eastern tunnels | Disable the lever with a ranged attack |
| Tripwires | Refugee escape hallway | DC 17 Perception, DC 15 Sleight of Hand |
| Grease | Aelis’s lair and nearby routes | Avoid slipping, control movement, watch fire |
| Oil | Area north of Arabella’s cave | Avoid fire and forced movement |
| Explosive or fire interactions | Aelis’s area | Separate enemies and control the battlefield |
| Buried chest traps | Treasure Room | DC 25 Perception, DC 15 Sleight of Hand |
| Locked chests | Treasure Room | DC 7 or DC 20 Sleight of Hand, depending on chest |
| Difficult terrain | Sewage channels and greasy slopes | Use jumping, ranged attacks, mobility spells or turn-based mode |
Recommended exploration route
This route is not mandatory, but it reduces backtracking and lets you collect the waypoint, Sarin’s Skull and the main fixed rewards before moving into the adjacent subareas.
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For a thorough but orderly visit
- 01Enter through the Basilisk Gate or Knights of the Shield Hideout route.
- 02Search the entrance storerooms before moving into the fumes.
- 03Disable the noxious-fume vents.
- 04Resolve the Bhaalist target-practice scene.
- 05Disarm the refugee escape route.
- 06Unlock the City Sewers waypoint.
- 07Visit Arabella’s cave if her earlier storyline is active.
- 08Explore the oily area and buried chest.
- 09Take the sewage raft towards Aelis’s lair.
- 10Decide whether to negotiate with or fight Aelis.
- 11Search his locked room and collect his loot.
- 12Investigate the northern room and loose stones.
- 13Continue north to activate the Undercity Ruins waypoint.
- 14Collect Sarin’s Skull from Bareki if completing Sarin’s funeral.
- 15Return to Aelis’s lair and restore Sarin.
- 16Visit the northern pier for Lorna and any Cazador-related environmental details.
- 17Check for Voss if the Orpheus or Lae’zel quest is active.
- 18Travel west to the Treasure Room through the Flymm Cargo connection.
- 19Complete the kobold map and dirt-mound cache.
- 20Continue into the Abandoned Cistern only when ready to pursue the Stone Lord thread.
Named directory
Named characters
Some entries are deceased, conventional or conditional appearances rather than permanent residents. Gandrel, Chessa and Kass depend on earlier Astarion and Gandrel outcomes. Arabella depends on her survival into Act Three.
Named documents and literature
The location page also lists several missing-child posters and sewer-related notes. Some are environmental documents rather than quest objects.
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Places and facilities
Named items
Quests and activities
The Lower City Sewers are associated with the following quests and quest threads:
The Guildhall, Abandoned Cistern and Undercity Ruins have additional quests of their own. Their inclusion in this directory indicates a connection through the sewer network, not that every associated scene takes place inside the named Lower City Sewers location.
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Quests and activities
Lore and environmental storytelling
The sewers show how much of Baldur’s Gate’s hidden life exists beneath the respectable city. Official notices and environmental writing refer to gutter kobolds once being contracted to maintain the sanitation tunnels, although they appear to have been killed or driven away. The area is therefore not merely an abandoned dungeon. It was once part of the city’s working infrastructure.
Its current occupants reveal the city’s political and supernatural pressures:
The missing-child posters, broken mirrors and silverware near Cazador’s route are particularly effective environmental reminders of the Gur children and Astarion’s past.
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Sources
- Lower City Sewers - bg3.wiki — bg3.wiki
- Lower City Sewers - bg3.wiki — bg3.wiki