What to Do in the Underdark (BG3): Your Complete Act 1 Checklist 🕸️

The Underdark in Baldur's Gate 3 is one of the most rewarding—and dangerous—zones in Act 1. Packed with hidden quests, unique companions, powerful loot, and story-altering choices, it's easy to miss crucial content if you rush through. Here's what you absolutely should do before leaving.

🗺️ Key Areas to Explore

Area| Why Visit?| Notable Loot / Quests
---|---|---
Myconid Colony| Meet Sovereign Spaw, decide Glut's fate| Spawn or Glut questline , tadpole upgrades
Arcane Tower| Solve puzzles, help a lonely dog| Light of Creation , Staff of Arcane Blessing
Sussur Tree| Craft a unique silenced weapon| Sussur Bark , Phalar Aluve (magic sword)
Festering Cove| Fight Hook Horrors, meet Duergar| Duergar questline , Scroll of Invisibility
Grymforge| Free Nere or side with slaves| True Soul quest , explosive barrels puzzle
Zhentarim Outpost| Hidden merchant with rare gear| Magic weapons , potions , gold

✅ Must-Do Activities (Don't Miss These!)

1. Save Baelen Bonecloak

  • He's stuck near a chasm. Toss him a Scroll of Misty Step or use telekinesis.
  • Reward: Access to his shop later in Act 2.

2. Craft the Sussur Weapon

  • Defeat the Hook Horror near the Sussur Tree.
  • Collect Sussur Bark and bring it to Blade of Frontiers camp blacksmith.
  • Creates a silent-effect weapon —great for stealth builds.

3. Complete the Arcane Tower

  • Visit the dog's grave south of the Sussur Tree first (trust me).
  • Solve the moonstone puzzle to disable turrets.
  • Loot includes one of the best staves in Act 1.

4. Decide the Myconids' Fate

  • Help Sovereign Spaw kill Glut, or help Glut overthrow Spaw.
  • This choice echoes into later acts and affects available allies.

5. Free (or Betray) Nere at Grymforge

  • Use explosive barrels to free the trapped Duergar leader.
  • Side with him for short-term loot, or free the slaves for long-term consequences.

6. Upgrade Your Tadpole

  • Talk to Borac near the Myconid Colony.
  • Bring him alchemy ingredients to unlock extra Illithid powers (without full transformation).

7. Loot the Zhentarim Hideout

  • Hidden in the northeast corner.
  • Packed with potions, scrolls, and gear you won't find elsewhere.

🧭 How to Enter the Underdark (4 Ways)

You can reach the Underdark through multiple Act 1 routes:

  1. Goblin Camp Moon Puzzle – Solve the floor puzzle in the Shattered Sanctum.
  2. Zhentarim Hideout – Behind an illusionary wall in the wolf room.
  3. Blighted Village Well – Drop down and navigate the underground tunnels.
  4. Hag's Lair (Overgrown Tunnel) – After defeating Auntie Ethel, pass through the illusionary door.

💡 Pro Tip: Finish as many surface quests as possible before descending. Some NPCs and options become unavailable once you leave.

⚠️ Dangers & Prep Tips

  • Bring light sources or cast Light /Daylight —many areas are pitch black.
  • Stock up on potions —healing, invisibility, and fire resistance help.
  • Save often —unexpected ambushes (Hook Horrors, Spectators, Duergar) are common.
  • Avoid long rests in open areas—enemy patrols can interrupt.

🕰️ Why This Matters in 2026 Playthroughs

As of 2026, speedrunners and lore hunters still debate the "optimal" Underdark route. Forum discussions on Reddit and Steam highlight how early choices here—like sparing Glut or freeing Nere—can unlock alternate endings and companion arcs in Act 3. Many players now treat the Underdark as a make-or- break zone for roleplay depth.

"The Underdark isn't just a tunnel to Act 2—it's where your story truly branches." – Popular BG3 community sentiment

TL;DR

Before exiting the Underdark in BG3:

  • ✅ Visit all 6 major zones
  • ✅ Craft the Sussur weapon
  • ✅ Decide Myconid & Duergar fates
  • ✅ Loot Zhentarim & Arcane Tower
  • ✅ Upgrade tadpole with Borac

Miss these, and you'll regret it in Act 2. Information gathered from public forums or data available on the internet and portrayed here.