Secret Mine

The Secret Mine is the fourth mansion that Luigi goes to in Luigi's Mansion: Dark Moon. This is the shortest mansion mission-wise, with 3 missions instead of the usual 5, a boss mission and a bonus mission after capturing the Boos in the area.

This mansion is located on a snowy mountain, which causes the mansion to be frozen over, inside and out. Also, as the name implies, the mansion was built near a now abandoned mining area, which Luigi explores. Professor E. Gadd sends Luigi to the Chalet where a group of Toads were studying the ghosts. When Luigi finds a Blue Toad he does a little dance causing the ice under their feet to break and they drop into a cave. The Chalet is built just above an abandoned mine that Luigi needs to explore. Aside from the ghosts, this is also home to a few Fuzzballs that follow Luigi, but don't actually hurt him.

History
The mine near the Chalet was original a secret mining project run by an unnamed company. It is unknown why the mines were abandoned but years of neglect have caused it to become flooded with snow and ice. The mine contains crystals with special properties. One of the properties of the crystals is that they strengthen ghosts that go inside the crystals for a certain amount of time. The Boos collect a large amount of crystals and take them elsewhere. At the bottom of the mine Luigi encounters several Boos where they strengthen up normal ghosts, causing them to become more powerful and gain white crystal markings all over the body.

In-game description
''Some determined geologists started a mining operation in these snowcapped mountains. But when the ghosts started moving in, they got scared and abandoned it!''

Some determined geologists set up a mining operation in these snow-capped mountains, but they got scared and abandoned it after the ghosts moved in! (PAL version)

Objects

 * 13 Sapphires

Bosses

 * Mini-bosses: A Strong Greenie, Strong Slammer, and a Strong Gobber
 * Boss: Shrewd Possessor

First Floor
(Ground Floor in PAL version)
 * Chalet Approach
 * Chalet
 * Smokehouse
 * Ice Lake
 * Fishing Hut

Basement 1

 * Skip Slope (Icy Slope in PAL Version)
 * Crossroads
 * Airway
 * Basin
 * Drift Hall (Drift Passage in PAL Version)
 * Prospector's Crossing (Prospector's Path in PAL Version)
 * Terminal (Station in PAL Version)
 * Under the Ice
 * Gondola
 * High Wires
 * Workshop Landing
 * Maintenance Room
 * Workshop

Basement 2

 * Shaft
 * Smuggler's Hideout
 * Skip Slope

Basement 3

 * Shaft
 * Coward's Chasm
 * Cinder Mine
 * Deep Hall (Deep Passage in PAL Version)
 * Crystal Quarry
 * Pit Mine

Other

 * Frozen Pit

Trivia

 * King Boo can be seen in the Ice Lake during the first mission, and then near the Workshop in the third mission.
 * This is the only mansion that the Polterpup can't be found at.
 * It's the only mansion that has three missions in the entire game, not counting the boss fight or the extra mission.
 * It's also the only mansion in the game to have a floor that is unknown excluding King Boo's Illusion.