Underworks is an industrial, mechanical zone filled with molten hazards, crumbling platforms, and enemy ambushes. It serves as both a transition point (between Whiteward, The Cauldron, and Wisp Thicket) and a place full of secrets. You’ll likely need upgraded movement tools like the Clawline or wall-jumping abilities to fully explore.

Beyond Fleas, Underworks contains:

  • Crafting materials such as Craftmetal.
  • Tool upgrades like the Delver’s Drill.
  • NPCs who expand the world’s lore and sell unique goods.

Lost Flea locations in Underworks

Here’s a breakdown of both Fleas and how to reach them.

Flea 1: Lava chamber Flea

  • Map position: Middle-left Underworks, marked on your map above.
  • Path: Enter the lava chamber filled with explosive mechanical bugs. Descend to the bottom, then head left through a door.
  • Hazards: Lava floor that deals continuous damage, plus exploding insect enemies and a stronger foe near the cage.
  • Requirements: At least one mobility upgrade is helpful, such as Clawline, to avoid damage and make jumps.
  • Reward: Standard Flea rescue—counts toward the Lost Fleas quest, advancing the Caravan.

Flea 2: Eastern corridor Flea (Speculated as per Map Release)

  • Map position: Middle-right Underworks, near the border with The Cauldron and above the route into Wisp Thicket.
  • Path: Found in a lower corridor; requires navigating through tighter tunnels with enemies. Some players report needing to spot a slightly hidden passage branching downward before reaching The Cauldron.
  • Hazards: Narrow spaces full of mechanical enemies, ambushes in small rooms, plus possible platforming challenges.
  • Requirements: Easier with advanced mobility—Clawline and strong healing setups help here.
  • Reward: Adds a second Flea to your Underworks tally, important for reaching higher caravan thresholds.

Tips for Surviving Underworks

  • Upgrade Movement First: The Clawline and wall-jump abilities aren’t strictly required, but they turn risky detours into manageable routes.
  • Carry Extra Healing: Enemies deal chip damage in swarms, while environmental hazards can punish mistakes harshly.
  • Scout Hidden Paths: Many secret passages are tucked just out of sight—watch for crumbled walls, broken pipes, or tunnels below the main route.
  • Fight or Flee: Ambushes often test your resource management. Sometimes, it’s safer to evade enemies instead of forcing combat.
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Underworks Fleas and Beyond

The two Lost Fleas hidden within the Underworks highlight both the danger and the reward of exploring this industrial labyrinth. The Lava Chamber Flea is straightforward but hazardous, testing your movement skills against molten floors and explosive enemies. The Eastern Corridor Flea, on the other hand, is more speculative and widely considered trickier—its narrow tunnels, ambushes, and hidden passages demand sharper awareness and advanced mobility.

Rescuing Fleas isn’t just about exploration; each one plays a role in advancing the Caravan, unlocking new thresholds of support, items, and lore that shape your journey. That’s why the Lost Fleas are given such weight—they represent progress, community, and the hidden rewards of perseverance. Finding them all in the Underworks is not just a side task, but a milestone that deepens both gameplay and story.