Warning! At least some content in this article is derived from information featured in Harry Potter: Magic Awakened. As such, spoilers will be present within the article.

The Underground Chambers^[2] were a series of rooms below Hogwarts School of Witchcraft and Wizardry, serving as the defences protecting the Philosopher's Stone from 1 August 1991 until 4 June 1992.^[1] There were a total of seven chambers, each of which containing an obstacle or task that guarded the Stone and delayed any intruder.^[1]

Background

In 1991, the Philosopher's Stone became the target of Lord Voldemort due to its potent ability to return him to full power. Suspecting danger, Albus Dumbledore set out Rubeus Hagrid to retrieve the Stone from Vault 713 at Gringotts Wizarding Bank the same day he took Harry Potter to Diagon Alley. That same day, Quirinus Quirrell, who was being used as the parasitic host of Lord Voldemort, broke into the bank, but failed to obtain the Stone.^[1]

Thereafter, Hagrid brought the Stone to Hogwarts as requested, and Professors Pomona Sprout, Filius Flitwick, Minerva McGonagall, Quirinus Quirrell and Severus Snape, as well as Hagrid and Dumbledore themselves, each created their own separate chamber.^[1]

Obstacles

Main article: Skirmish in the Underground Chambers

Order of encounter   Obstacle (Preparer)	Description
First Fluffy (Rubeus Hagrid)	The only known way to access the Stone was through a trapdoor in the third-floor corridor, which was guarded by the three-headed dog Fluffy. To get past this obstacle, one had only to play some music, which would then put Fluffy to sleep.[1]
Second Devil's Snare (Pomona Sprout)	Through the trapdoor and a long and dark drop through the air, led into a chamber full of Devil's Snare. The plant was designed to entangle and suffocate any intruders, especially quickly the more the intruder tries to escape. Bluebell Flames, however, could be used to scorch them.[1]
Third Winged Keys (Filius Flitwick)	A downwards sloping passage with stone walls, through which trickling water could be heard, led to a brilliantly lit chamber with a very high ceiling, full of glittering winged keys. On the opposite end of the chamber from the stone passage was a large, old-fashioned wooden door with a silver lock that would not open, even with the Alohomora Charm, without the necessary key. One had to mount a broom and attempt to pursue the correct key; all of the keys fluttered away quickly, darting around, making it very difficult to catch the correct one.[1]
Fourth Chessboard Chamber (Minerva McGonagall)	"I think we're going to have to be chessmen." — Ron[src] This chamber was so dark that it was impossible to see anything. It contained a Human Chess Game. To get across the chamber, one had to checkmate the King according to the rules of Wizard's Chess.[1]
Fifth Mountain troll (Quirinus Quirrell)	"I do say I have a gift with trolls." — Quirrell discussing his chamber[src] A chamber containing a mountain troll at the entrance; it had a foul odour in it, and it was said that there was great relief in passing through it.[1]
Sixth Potion riddle (Severus Snape)	Upon entering the chamber, the entrance was blocked by purple flames, whilst the exit was covered by black flames. A table holding seven unlabelled potion bottles of differing shapes and sizes sat in the centre of the room, with a logical riddle. Three were poison, two contained nettle wine, one contained a potion to safely traverse the black flame, and the last contained a potion that allowed passage back through the purple flames. The riddle, when properly worked out, revealed the contents of each bottle, and therefore which one was safe to drink to allow onward progress.[1]
Seventh Mirror of Erised (Albus Dumbledore)	"You see... Only a person who wanted to find the stone. Find it, but not use it, would be able to get it." — Albus Dumbledore[src] The chamber contained the Mirror of Erised. The only way to obtain the stone was for an individual to look into the mirror and see themselves possessing the stone but not using it.[3]

Behind the scenes

• The prevalence of the number seven is not coincidental; seven obstacles were in place to get to the Philosopher's Stone and seven different potions were available in Snape's logic riddle. Seven, as deduced by Arithmancer Bridget Wenlock, has magical properties to it. It is believed that the number seven is the most magical number. It is also, of course, the total number of books in the series, (with Rowling firmly sticking to that number), and the number of pieces Voldemort desired his soul to be in (as he recognised the significance of the number seven and believed it to be the greatest).
• The fifth and sixth obstacles were cut from the film adaptation of Harry Potter and the Philosopher's Stone.
  • The potion riddle, however, was later shown in the second disc.
  • The potion riddles and other obstacles cut from the film do appear in the different versions of the game.

Appearances

• Harry Potter and the Philosopher's Stone (First appearance)
• Harry Potter and the Philosopher's Stone (film)
• Harry Potter and the Philosopher's Stone (video game)
• LEGO Creator: Harry Potter
• LEGO Harry Potter: Building the Magical World
• LEGO Harry Potter: Characters of the Magical World (Mentioned only)
• LEGO Harry Potter: Years 1-4
• LEGO Harry Potter
• Harry Potter for Kinect
• Pottermore
• HarryPotter.com
• Harry Potter: The Creature Vault
• Harry Potter: Magic Awakened (In the Book with No Name)

Notes and references

Below the ground floor of Hogwarts Castle
Classrooms
Alchemy Class · Defence Against the Dark Arts dungeon · Potion-Mixing Room · Potions Classroom
Common rooms
Hufflepuff Basement · Hufflepuff Boys' Dormitory · Hufflepuff common room · Hufflepuff Girls' Dormitory · Slytherin Boys' Dormitory · Slytherin common room · Slytherin Dungeon · Slytherin Girls' Dormitory
Corridors
Boathouse passageway · Corridor of Secrets · Dungeon cave · Dungeon Corridor · Forgotten Cavern · Hidden Herbology Corridor · Hieroglyphic Hall · Kitchen corridor · Lost Tunnel · Lower Chambers Corridor North-East · Lower Chambers Portrait Corridor · Lower Chambers Corridor West · Poltergeist Passage · Porticus Circumscriptus · Porticus Periculum · Porticus Imago · Porticus Medius · Prowling Passage · Quidditch cave · Secret way to Slytherin Common Room · Slytherin Corridors · Undercover route to the Kitchens · Unexplored passage to Hogsmeade · Way to Courtyard · Way to the Forbidden Forest
Halls and rooms
Athenaeum · Athenaeum antechamber · Bottom of the Well · Campaign Room · Cauldron Room · Chamber of Secrets · Conical Crypt · Dark Hall · Deathday Ballroom · Deathday Party Hall · Duelling Room · Dungeons · Dungeon Chamber · Dungeon Five · Dungeon foyer · Dungeon hall · Dungeon Pit · Dungeon Portrait Room · Forgotten Dungeons · Grate Chamber · Kitchens · Map Chamber · Potions Classroom adjoining room · Potions Classroom dungeons · Room of Doom · Room of Runes · Shop · Slug Pit · Slytherin Duelling Dungeon · Undercroft · Vestibule of Mischief · Werewolf Saga Tapestries room
Offices
Secret study beneath Greenhouse One · Severus Snape's office · Slytherin's Scriptorium
Other locations
Boathouse · Dungeons cell · House-Elf Living Quarters · Lever Rooms · Lower Hogwarts Castle · Keepers' Caverns · Troll Bedroom · Underground Harbour · Underground Chambers
Portraits, statues and other artwork
Basil Fronsac · Bearded man with book · Bloody Baron · Cecilia Gallerani · Charles Rookwood · Emily · Elizabeth Burke · Hooky · Horace Slughorn · Howard · Mad old man · Mopsus · Niamh Fitzgerald · Old man · Percival Pratt · Percival Rackham · Unidentified Ravenclaw lady · San Bakar · Salazar Slytherin · Sleeping Dragon Statue · Severus Snape · Sleeping hermit · Slytherin Dungeon tapestries · Urn of Ashes
Staircases
Detention Escape Route · Dungeon foyer exit · Dungeon Staircase · Grand Staircase · Slughorn's Staircase · Slughorn's Stairs · Staircase from the Restricted Section to the Athenaeum antechamber · Staircase to the Quad
Storerooms
Basement · Firefly Room · Neville Longbottom's storeroom · Potions basement · Restricted Section storage room · Store Room · Troll Storeroom