Operate the water valves, guide Luigi’s rubber duck through the sewers and drain the system before fighting Clem. A later return with Toad opens the Old Reservoir and the last gem.
Valve room
Use Gooigi’s pipes to reach switches and keys while Luigi controls the water valves. Before sending Gooigi through a pipe, turn off the water pouring over its exit. The yellow gem is on the scaffold behind the starting pipe wall.
Main Tank and Storage
Explore the storage closet left of the central tank. Move the mop bucket for the red-gem pipe puzzle. Luigi must change the valve setting twice so Gooigi can cross the hidden rooms and collect the gem without being dissolved.
Observation
Restore the missing pipe with Dark-Light and flash the coffee console for the blue gem. Continue toward the sewer controls. During the later Toad visit, restore the speaker console on the left wall with Dark-Light and activate it for the music achievement.
Rubber-duck route
Luigi navigates the water while Gooigi uses dry pipes and gate controls. At each sluice, stop Luigi in a safe position, switch to Gooigi and open the next gate. Avoid the water jets and shark hazards; steering slowly near an opening is safer than hitting the edge at full speed.
Drain the sewers
Reach the far switch and lower the water. Walk back along the now-dry sewer route. Use the lift in Sewer B for the green gem and the periscope pipe in Sewer C for the submarine’s purple-gem cooking puzzle.
Clem
Leave Gooigi on the dry bank near the ladder. In the pool, avoid bombs and spin Clem’s duck with the Poltergust until he is dizzy. Push him into the spiked edge, switch to Gooigi and capture him on land before he returns to the pool. Repeat until the 10F button is released.
Later Toad mission
After first reaching 12F, E. Gadd sends Luigi back for the missing upgrade parts. Find Toad, use him as a projectile to break obstacles and open the Old Reservoir route. The white crystal ghost there completes B2’s six gems. Follow the separate Super Suction chapter for that return.
Gems and floor completion
Use the six-colour list to finish this floor. Check the required return visit before trying a route that needs Gooigi, Super Suction or the later Toad mission.
- All six gems — B2 — Boilerworks
- Boo locations and capture method
- Floor achievements and full checklist
Continue the walkthrough
Next: