Main Tank

The Main Tank is a location in Luigi's Mansion 3. It is found in the Boilerworks on the second basement floor of The Last Resort, located north of the Reservoir.

When Luigi first arrives the Main Tank, he encounters Clem sleeping at the Top. Luigi attempts to avoid waking him up again, only to end up stepping on a rubber ducky yet again, waking him up. An irritated Clem then tries to prank Luigi one last time by filling the reservoir again. However, after Luigi rides an inner tube shaped like a duck, saves himself, and reaches the top because of the water, Clem decides to confront Luigi personally. During their battle, Luigi ultimately defeats Clem before proceeding to drain the reservoir to get the tenth floor elevator button.

When Luigi visits the Main Tank again, a Boo can be hiding.