The Great Lake

• Type: Natural Body of Water
• Location: South of Hogwarts Castle, on the grounds of Hogwarts School of Witchcraft and Wizardry, Scotland, Great Britain
• Owner/Residents: The Giant Squid, a colony of Merpeople, and various other magical creatures including Grindylows.
• Key Features: A large, deep, and dark body of water; home to a variety of magical aquatic life; a traditional part of the first-year students' arrival at Hogwarts; the site of the Second Task of the 1994 Triwizard Tournament.

The Great Lake, often referred to as the Black Lake, is a vast, deep body of water located on the Hogwarts Grounds. Its surface can vary from being as smooth as black glass to choppy and icy grey, depending on the weather. The lake is a fundamental part of the Hogwarts landscape and has been present since the school's founding. The lake is teeming with magical life. Its most famous inhabitant is a Giant Squid, which is largely placid and has been known to interact harmlessly with students, even saving Dennis Creevey after he fell from a boat. A reclusive and territorial colony of Merpeople inhabits a village in its depths, complete with crude stone dwellings and a central statue. These Merpeople are wary of wizards and witches, possessing a harsh, screeching language when above water but a more comprehensible one beneath the surface. The shallows of the lake are also infested with aggressive water demons known as Grindylows. For centuries, the Great Lake has been the final leg of the journey for new students. First-years traditionally cross the lake in a fleet of small boats, guided by the Groundskeeper, which provides them with their first breathtaking view of Hogwarts Castle. During the 1994-1995 school year, the lake also served as the mooring point for the spectacular, skeletal ship from the Durmstrang Institute.

The Great Lake is the setting for several significant events throughout the series.

• First-Year Arrival: In Harry Potter and the Philosopher's Stone, Harry Potter and his classmates make the iconic boat journey across the Great Lake, marking their formal arrival at Hogwarts.
• The Second Task: The lake's most prominent role is in Harry Potter and the Goblet of Fire as the arena for the Second Task of the Triwizard Tournament. The champions were required to swim to the bottom of the lake to rescue a hostage from the Merpeople's village within a one-hour time limit. Harry Potter used Gillyweed to breathe underwater, Cedric Diggory used a Bubble-Head Charm, Viktor Krum employed a partial Transfiguration into a shark, and Fleur Delacour was forced to retire after being attacked by Grindylows.
• Dumbledore's Funeral: At the end of Harry Potter and the Half-Blood Prince, the funeral service for Albus Dumbledore is held on the shore of the Great Lake. In a moving tribute, the Merpeople colony rose from the depths to pay their respects, demonstrating their high regard for the late Headmaster. Dumbledore's Tomb, a white marble sarcophagus, was placed by the water's edge.
• The Elder Wand: Following the Battle of Hogwarts in Harry Potter and the Deathly Hallows, Harry Potter stands on the banks of the lake with Ron Weasley and Hermione Granger. It is here he decides not to keep the Elder Wand for himself, but to return it to Dumbledore's Tomb.

• The Merpeople Village: Located deep in the center of the Great Lake, this village consists of crude stone dwellings decorated with carvings of Merpeople hunting the Giant Squid. A large, rough-hewn statue of a Merperson stands in a central square where the Triwizard Tournament hostages were held.
• The Shoreline: The banks of the Great Lake are a common place for students to relax, study, and walk between classes. Following his death, this area became the site of Dumbledore's Tomb.

• In the film adaptations, the Great Lake is almost exclusively referred to as the “Black Lake.” Loch Shiel, Loch Eilt, and Loch Morar in the Scottish Highlands were used as filming locations for the lake and its surroundings (film).
• According to Pottermore, the Slytherin Common Room and dormitories are located in dungeons that extend under the Great Lake, and their windows look out into its green, murky depths (Pottermore).
• J.K. Rowling has stated that the Giant Squid is a real, albeit mysterious, creature with a high degree of intelligence, rather than a magical beast in the formal sense (J.K. Rowling interview).