Luigi's Mansion 3 Guide: B2 Boilerworks Walkthrough

This portion of the Luigi's Mansion 3 guide covers the Boilerworks Walkthrough and all the Boilerworks gems (note: not all of these can be collected on the first run so you'll have to come back regardless). Here, you'll find step-by-step solutions to all the sewer puzzles plus tips and tricks for how to beat the mechanic boss while on the duck floaty.

The Boilerworks floor requires Gooigi and Luigi almost evenly. This is something to keep in mind if you're co-oping the campaign alongside another player. The majority of the level requires you to get good at navigating the waters on a duck floaty but move with caution, one pop and it's instant death.

Below are the walkthrough sections and objectives. Please note we may have added a few objectives ourselves to indicate the steps you need to take to complete the main objective.

You CANNOT get all these gems on your first visit but below are the gems available. Two of them will become available later in the campaign. This guide page will include all the ones you can get now. All gem locations will be written in a blue box so scroll through for them to see what you're missing or scroll past them if you'd rather discover the answer to those puzzles yourself.

Welcome to the Boilerworks.

Remember Gooigi melts when water touches his gooey flash. Have Luigi walk through the water burst and then use the vacuum to turn the valve above and shut the water off.

Vacuum up this flap to reveal the pipe. Have Gooigi enter the pipe to reach the platform with the key.

Vacuum up the flap to the right of the green pipe (and to the left of the valve wheel).

Have Gooigi travel through the pipe and grab the gold key.

Boilerworks Gem #6

Stay on the platform with the key, and walk to the left. Gooigi will not fall--as he is pictured behind the valve as a shadow--there is a ramp to the gem.

While you’re up here. Walk to the left (as Gooigi) and grab the gem on the upper section. It's hard to tell but you can, in fact, just walk over there from this wooden platform.

Head to the next room. Fight off the ghosts waiting for you and have Gooigi go down the green pipe.

Turn the valves above so that Gooigi can walk safely to the other side.

Turn all the valves to the right for Gooigi to enter the puzzle. Have him stand under the fourth pipe when you turn the valves to the left. Flash the strobulb light at the end of the pipes to activate the door above.

Have all the valves turned so that the arrow in on the right.

Move Gooigi so that he's under the middle pipe.

Then turn all the valves so their arrows are facing left.

Up ahead, you’ll spot some waterfalls and a fan. Step onto both buttons near the fan to activate it.

Vacuum the platform fan so it looks like this.

Vacuum the fan as Gooigi to rotate the platform to create a path from the general area to the yellow, encased ladder.

Keep adventuring, passing through the maintenance room?

Boilerworks Gem #3

Shine your dark light in this corner to reveal a water heater. Return to the far right corner to flash your strobulb and get the gem.

Shine your Dark Light onto the spot by the donuts, where the little burner is.

Flash the blinking light with your Stobulb to get some much-needed coffee and a gem.

Get into the floaty duck. Vacuum and blow air out to get a feel for how it controls.

To begin the Underground Sewer puzzles, have Luigi summon Gooigi on land, and then hop into the duck floaty in the water. Vacuum and blow to move in the water.

Approach the ladder while in the floaty and step onto dry land. Then summon Gooigi. Have him go through the green pipe and then through the green pipe above and to the left. This will spit him out from a pipe on the right, allowing him to suck up the chain hanging there to open the gate for Luigi to float through.

In the next area, approach dry land so you can send Gooigi through the pipe on the left.

Have Gooigi travel through this pipe to begin. For him to reach the ball and chain in the top right corner, Luigi must vacuum the valve in the water. This only lasts a few seconds.

As Luigi, float over to the right and vacuum up the valve to turn it until the water above (stopping Gooigi from walking further right).

At last, Gooigi can walk to the right, such up the chain, and lift the door for Luigi to continue.

Once Luigi's through the gate have Gooigi stay up top. Then, have Gooigi walk to the right.

Follow the pipes in this area to reach the ball and chain on this platform before Luigi can run into the spikes.

From here, have Gooigi travel through pipe after pipe (quickly!) until he's near the ball and chain. Have him pull it to open the gate. Note: if you’re playing alone consider moving Luigi as close to the front of the screen (where the camera is) as possible because he will keep floating towards the spiked door while you play as Gooigi.

Either have Gooigi continue forward (through gates and pipes) or approach dry land, summon him, and send him through the pipe on the left so he can be on the area above you.

Gooigi can travel through the pipes from above, or be summoned from this platform. Have him use the pipes to get to this point where he will need to time running under the pipes before they spew water.

As Gooigi, run underneath the pipes spewing water. Time it so that you don't get hit.

As Luigi, float a bit more to the left and vacuum up the ball and chain to open up a new pipe for Gooigi.

As Gooigi, head through that pipe so you can keep moving to the right. Up ahead are more pipes spewing water.

Time the water pipes again while Luigi holds the ball and chain below. Once the "sharks" appear, try to get past them as quickly as possible without hitting them. There's not a good trick to it other than by moving around and having them follow you rather than chase.

Finally, have Gooigi pull the ball and chain to open the spiked door but watch out for the shark ghosts. Avoid them because one hit pops your floaty.

Once you’re past the sharks you’ll need to take care of some ghosts before figuring out how to get Googi to the top.

As Luigi, turn the valve on the left (vacuum it) so that the arrow faces right and turn the right valve (blow on it) so the arrow faces up.

Have Gooigi go through the pipes and then turn the valve so the arrow faces up (vacuum it).

Turn the valves so that they look like this. The direction the light is on is the direction Gooigi will travel in the pipes. Pull the red lever behind Gooigi at the top to continue.

Return to the bottom area, and have Gooigi go through the pipes again. This time, he’ll make it all the way to the top.

Use the suction shot to pull the lever at the top.

Go back through the puzzles you just did, but on the ground.

Return back the way you came from, but now you can just walk.

There will be several shark ghosts flopping about. Defeat them by doing a ground slam to knock off their fins and goggles, flashing them with your flashlight, and then ghost slamming them into oblivion.

Boilerworks Gem #5

Look for this pipe in the ground and use the suction shot. Have Gooigi travel down it.

While in the ghost "shark" area, pull the metal cap off the pipe in the ground. (Note: the cap has an open slot you can look through). Use Gooigi to enter the pipe. Once you're down there, in the submarine.

Vacuum the flaming log on the left. Walk to over to light the stove on the right.

Vacuum up the log on the other side of the submarine, and then light it under this stove. The gem will pop out of the pot above it.

Once the water in the pot boils, a gem will pop out

Boilerworks Gem #4

Stand Gooigi on the platform and have Luigi pull the chain. Vacuum and blow to rock the gem off the hook it's stuck on.

Use Luigi to pull the ball and chain at the bottom of the platform, and Gooigi vacuums the gem down from the chain it is stuck on.

It takes some time and a few attempts so don't get discouraged.

Interact with the ladder to knock it down then walk over the movable platform and up the yellow ladder. Turn the valve with your vacuum and head through the door.

The mechanic ghost battle is in water, similar to the puzzles before his encounter.

Avoid the explosives he drops and stay away from the edge of the pool because of the spikes.

You can't use your flashlight to stun the mechanic but you can stun him by waiting for him to spin himself dizzy or getting him to get hit by one of his explosives.

Stun the mechanic ghost once he spins himself dizzy. Vacuum him up and shoot him into the spikes along the side of the pool.

Once he's stunned (spinning with little duckies floating above his head), vacuum him up and shoot him into the spikes. Shoot him so he lands relatively close to the ladder.

After that, quickly head for the ladder and run towards him before he can get up and put his floaty back on. Flash him with your flashlight, and proceed to ghost slam him.

Shoot the mechanic as close to the ladder as possible. Once he's on the ground, run to him and stun him again to ghost slam.

Repeat the process a few times to capture him.

Exit the pool and head to the red switch. Use the plunger to pull it to drain the pool.

Take the ladder down to the bottom of the drained pool. There are things to interact with down here, but they do not drop any coins or cash.

The button is at the bottom of the pool. The switch to drain it is at the top.

Grab the button and exit at the bottom right of the room.

Take the ladder down and go through the door that is closest to the back left of the room with the rotating platform. Follow the path to the elevator.

Oh yeah!

Put the button in the elevator and head to the 10th floor to explore the Tomb Suites.