Hogwarts secret passages

Harry Potter: "Neville?"

Neville Longbottom: "I knew you would come!"

Harry Potter: "The Room of Requirement?"

Neville Longbottom: "This is the only way in or out now. The grounds are crawling with Death Eaters and Dementors."

— Harry Potter is surprised that the passage leads to the Room of Requirement, as Neville Longbottom explains that

There exist many Hogwarts secret passages. Most are internal to the castle, such as a stairway hidden behind a tapestry. Several lead from the castle or school grounds past the boundaries, presumably to the nearby wizard village of Hogsmeade.

Passages out of school

The Marauder's Map

During the 1993-1994 school year, Fred and George Weasley revealed and gave the map to Harry Potter so he could use a secret passage to get to Hogsmeade, since he didn't have a signed permission form, and Dementors were patrolling the boundaries. They said they acquired it from Argus Filch's Office during their first year at Hogwarts (the 1989-1990 school year). They demonstrated the map, showing seven secret passages leading to Hogsmeade, and which one was most likely known only by them.

These 7 are:

• A passage beneath a one-eyed witch statue by the stairs to the Defence Against the Dark Arts classroom, leading to the cellar of Honeydukes. Tapping the hump with a wand and speaking aloud the word Dissendium to the witch makes the hump on the statue open just wide enough for a small person to slide down to the hidden passageway. No password seems to be needed to return to the school. Harry Potter used this twice to get to and from Hogsmeade in the 1993-1994 school year. There was no report of break-in at Honeydukes, and it is unknown whether Sirius Black used it when he broke into (or fled) Hogwarts Castle.
• A passage behind a mirror on the fourth floor, which was caved in as of 1993. It leads to Hogsmeade, but exactly where is unknown. Sirius Black mentioned that it was large enough for an organisation to hold a meeting inside.
• A passage beneath the Whomping Willow, leading to the Shrieking Shack. It was created for Remus Lupin to use during his school years so that he could isolate himself during his monthly transformations into a werewolf. Sirius Black may have used this passage to slip past the Dementors and get inside the school grounds during the 1993–1994 school year.

A path from beneath the Whomping Willow leads to the Shrieking Shack

• A passage behind the statue of Gregory the Smarmy. Fred and George Weasley claimed to have found this secret passage during their first week at Hogwarts (likely before they acquired the Marauders Map).
• Three unspecified secret passages, apparently known to Argus Filch.

The Vanishing Cabinets

Peeves is the one who smashed one of the two vanishing cabinets, after being convinced to do so by Nearly Headless Nick

• A link between two vanishing cabinets, one in Hogwarts and the other in Borgin and Burkes in Knockturn Alley. This link presumably worked until 1992 when Peeves (persuaded by Nearly Headless Nick) smashed the Hogwarts cabinet on the floor above Argus Filch's office. The passage was reopened in 1997 when Draco Malfoy fixed the cabinet, and used it to bring Death Eaters into the school. This passage is not shown on the Marauder's Map.

The Room of Requirement

• A passage in the Room of Requirement, leading to the Hog's Head bar in Hogsmeade. This passage opens from the Room of Requirement when one there has need of food. Once one reaches the end, the portrait of Ariana Dumbledore swings open in the 2nd floor of the Hog's Head above the fireplace. Apparently, Aberforth Dumbledore could not open the passage from his side when the Room of Requirement was in use, but had to send Ariana's portrait to summon Neville Longbottom to open her portrait. It was discovered by Neville Longbottom during the 1997–1998 school year and it is not shown on the Marauder's Map.

Due to the nature of the Room of Requirement, it is possible that several passages to different locations outside of Hogwarts could be accessed from it.

Who knows?

• Dumbledore, Madam Pomfrey, (perhaps some staff members), the Marauders and Severus Snape knew of the secret passage under the Whomping Willow. Hermione's cat, Crookshanks learned about it from Sirius Black and knew how to immobilise the Whomping Willow to get past it.
• Sometime during their school years, Remus Lupin, Peter Pettigrew, Sirius Black and the late James Potter discovered 7 secret passages out of school and wrote them on the Marauders Map. It is unknown who, if anyone they informed. The map next fell into the possession of Argus Filch, who was unlikely to have ever been able to use it.
• In the 1993-1994 school year, Fred and George Weasley said Argus Filch knew of four of the seven secret passages out of school shown on the map; the fourth likely being the one behind the statue of Gregory the Smarmy.
• As of 1994, the authors of the Marauders Map, and its possessors (Fred Weasley, George Weasley, Harry Potter, but not Argus Filch) and their confidants knew of all seven secret passages.
• Apparently as of the 1993-1994 school year, many of the staff did not know about the secret passage behind the one-eyed witch. After Sirius Black gained admittance to Gryffindor tower in 1994, security inside the castle was increased. Professor Lupin knew of it and Professor Snape may have suspected a secret passage there, yet no added security measures (e.g. Security Trolls) seemed to have been placed there.
• Upon rejoining the Order of the Phoenix in 1995, it is likely Remus Lupin and Sirius Black informed Albus Dumbledore about all 7 of these secret passages, and he in turn may have informed Severus Snape and other members of the Order of the Phoenix.
• In 1997, Aberforth told Harry and his companions that all the old secret passages were blocked (meaning the 7 on the Marauders Map). Therefore it is likely Professor Snape, and the Carrows knew to guard it.
• It is unknown whether or how many Death Eaters used secret passages to enter the grounds or the castle during the Battle of Hogwarts. It is likely Peter Pettigrew told Lord Voldemort all he knew about the secret passages, either by 1981 or after he rejoined him in 1994.

• In the 1995-1996 school year Fred and George Weasley threw Montague, a member of the Inquisitorial Squad, into the broken Vanishing Cabinet, where he disappeared and was trapped. He was finally able to disapparate and re-appeared in a Hogwarts toilet. He recounted his experience of sometimes hearing people in Hogwarts and other times people in Borgin and Burkes. From this, Draco Malfoy realised that the two cabinets created a passage and that if he could fix the broken one then he would have a secret passage into Hogwarts. He did this and brought Death Eaters into Hogwarts, boasting to Professor Dumbledore (and an invisible Harry potter) before fleeing with Snape through the front gates. Harry Potter then informed Professor McGonagall, and those also present in the hospital wing, of this secret passage. What became of the Vanishing Cabinet in Borgin and Burkes is unknown. The other vanishing cabinet remained at Hogwarts in the Room of Hidden Things until it was likely destroyed in 1998 by Fiendfyre.

• Aberforth Dumbledore knew of the secret passage between his pub, the Hog's Head, and the Room of Requirement, since it involved the portrait of his sister, Ariana Dumbledore. Presumably, prior to the 1997-1998 school year, Albus Dumbledore may have been the only other person to know of it. This passage was discovered by Neville Longbottom during the 1997–1998 school year and used by members of Dumbledore's Army who were hiding out, then summoned for the Battle of Hogwarts along with the Order of the Phoenix and others. Finally most of the school was evacuated through this passage. How many of them would now know how to access the Room of Requirement in its unoccupied state and be able to open the passage?

Blocking the passages out of school

Around 1993, Fred and George Weasley reported that one passage on the Marauders Map had its ceiling collapse, and was impassible.

The 1996-1997 school year saw even stricter security measures on the castle, including the use of Secrecy Sensors to stop smuggling in of Dark objects and sealing the gates and boundaries to unauthorised entry. Since the Marauders, Remus Lupin and Sirius Black had re-joined the Order of the Phoenix the prior year, Professor Dumbledore may have blocked the known secret passages on the Marauders Map.

The passage into Hogwarts by the pair of vanishing cabinets was blocked when Peeves damaged the one at Hogwarts in the 1992-1993 school year, until Draco Malfoy repaired it in 1996. It is unknown whether the Ministry seized or destroyed the vanishing cabinet at Borgin and Burkes after the Battle of Hogwarts but before the Fall of the Ministry of Magic to prevent its further use as a passage to Hogwarts. The one at Hogwarts was likely destroyed by Fiendfyre in the Room of Hidden Things.

In 1997, Aberforth Dumbledore said that all the old passages into the school (meaning the 7 on the map) were blocked. During the Battle of Hogwarts, Fred and George Weasley said they'd help guard these passages against the Death Eaters.

When Aberforth left his pub to join in the Battle of Hogwarts, the secret passage through the Room of Requirement was closed. It is unknown whether anyone opened it or could have opened it from his pub, though over a hundred students and staff now knew where it was.

Secret Passages within the castle

There are minor secret passages within Hogwarts, such as a stairway hidden by a tapestry with a trick step. Argus Filch reportedly is familiar with all of them, so he can quickly cross the castle in pursuit of rule-breakers.

The Marauder's Map also showed rooms and secret passages inside Hogwarts that the Marauders discovered, but not those they did not discover (e.g. the entrance to the Chamber of Secrets and the Room of Requirement, but the latter may also have been due to its Unplottability).

When members of Dumbledore's Army were using the Room of Requirement as a hideout, they needed a secret exit, to avoid their enemies who might be guarding the normal entrance on the 7th floor. Neville Longbottom said that each day the exit led to a different place in the castle. The night of the Battle of Hogwarts, Harry found that he and Luna had exited to the 5th floor.

Pipes and the Chamber of Secrets: The Chamber of Secrets itself was far below the school, and someone had to ask the chamber door on that level to open with Parseltongue. But in order for a person to get down there, they'd have to use Parseltongue in Moaning Myrtle's Bathroom to open a secret passage into a pipe large enough for them to slide through to that level. During the 1992-1993 school year Harry Potter was hearing the Basilisk moving through the pipes in the walls, though he didn't know it at the time. Later when he slid down the pipe on the way to the Chamber of Secrets, he saw pipes branching off into other directions. These could have been secret passages for a large serpent to use, and might open in other parts of the school.

Appearances

• Harry Potter and the Philosopher's Stone (First mentioned)
• Harry Potter and the Prisoner of Azkaban (First appearance)
• Harry Potter and the Prisoner of Azkaban (film)
• Harry Potter and the Prisoner of Azkaban (video game)
• Harry Potter and the Order of the Phoenix (Mentioned only)
• Harry Potter and the Half-Blood Prince
• Harry Potter and the Half-Blood Prince (film)
• Harry Potter and the Half-Blood Prince (video game)
• Harry Potter and the Deathly Hallows
• Harry Potter and the Deathly Hallows: Part 2
• Harry Potter and the Deathly Hallows: Part 2 (video game)
• LEGO Harry Potter: Years 1-4
• LEGO Harry Potter: Years 5-7
• Harry Potter: The Character Vault
• Harry Potter: The Creature Vault (Mentioned only)