"Is this all real? Or has this been happening inside my head?"
The subject of this article is a real-life person, company, product, or creative work that has been mentioned "in-universe" in a canon source. The Harry Potter Compendium is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
The Forest of Dean is a geographical, historical and cultural region in the western part of the county of Gloucestershire, England. The forest is a roughly triangular plateau bounded by the River Wye to the west and north, the River Severn to the south, and the City of Gloucester to the east.[1] It is widely considered as a beautiful and calm place. There is a lake within this forest which contained at least one anglerfish.[2]
In 1928, Rubeus Hagrid was born in or near the Forest of Dean, where he developed his strong West Country accent.[3][4] The Forest of Dean once played host to Hermione and her parents during a camping trip for the summer holidays.[5]
Hermione: "The Forest of Dean. I came camping here once, with my mum and dad."
— Hermione and Harry upon their arrival at the forest.[src]
A few days after Christmas in 1997, Hermione Granger would return to this location with Harry Potter and would camp in the forest during their Horcrux search, trying to avoid captivity and staying in one place for too long. Hermione and Harry would take it in turns to watch the tent for trouble sharing one wand between them. Whilst there, the forest was snowy, and its lake was frozen.[5]
Harry Potter following the silver doe at the Forest of Dean.
It was during their stay in the forest that Severus Snape anonymously delivered Godric Gryffindor's Sword to Harry by placing it inside the frozen lake that resides in the forest and using his Patronus, a doe, to guide him to it. As Harry attempted to retrieve the sword from the lake, the locket horcrux around his neck began to strangle him. Fortunately for Harry, Ron Weasley, having previously abandoned his friends, rejoined the group and saved Harry's life. Ron then destroyed the Horcrux, Salazar Slytherin's Locket, with Godric Gryffindor's Sword.[5]
The Misty Dell, The Quarry and The Ruins within this forest was used to imprison enemies of the Death Eaters during this time and the Snatcher Camp was used by Snatchers for same purpose. An area of the forest have been infested by Acromantulas, called "The Acromantula", and the spiders began to imprison Muggle-borns. Also some Inferi infested the forest in the late 1997 winter periods.[6]
In the video game adaption they even set up a camp close to an abandoned closed-off viaduct.
J. K. Rowling lived on the southern edge of the Forest at Tutshill from 1974 to 1983, which might have been the influence of her putting the forest in the novel.[1]
Also in the film adaptation of Harry Potter and the Deathly Hallows, the Forest of Dean scene is extended with Hermione musing about her past relationship with the place and despairingly asking Harry if they should forget about their destinies and just stay in the forest and grow old together.
Forest of Dean on Wikipedia