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The Grotto Lounge is a location in Luigi's Mansion 3. It is found in The Spectral Catch on the twelfth floor of The Last Resort. It is north of the Elevator Hall and south of the Beach. The white gem can be found here.
The Grotto Lounge is a pirate-themed restaurant with waterfalls, skulls, candles, lanterns, coconuts, and barrels. Luigi can use the Suction Shot or Burst to break open the barrels, revealing a bit of treasure. Along the way, there is also a disguised Possessed Chest. Luigi can defeat, then open, it to get some Gold Bars. When Luigi approaches the large skull at the end of the grotto, it opens to reveal the doors opening the way to the beach.
After returning from the beach, Luigi can fire the yellow Toad into an opening in the wall east where the Possessed Chest was. If launched correctly, the Toad will pick up some Gold Bars before dropping out.
The white gem is in the southwest of the grotto, held in the mouth of a skull above a crate. Luigi can use the Dark-Light Device to reveal string attaching the skull to the crate, with a handle at the bottom. Luigi can vacuum and yank the handle to raise the pirate flag to the top of the contraption, opening the mouth of the skull and dropping down the gem.
The Grotto Lounge cannot be accessed until after Luigi has unlocked the Super Suction, allowing him to clear away the large ship blocking the doors in the elevator hall.
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