The Black Lake

The Black Lake is a large body of water located to the south of the castle. It is about 1/2 a mile in diameter and the Hogwarts plumbing network drains into it.

Every school year at Hogwarts, 1st years sail across the lake to the castle that is led by Rubeus Hagrid in boats as part of Hogwarts tradition. When they get to the school, then they are sorted into their houses. In Harry's fourth year it is said that Dennis Creevey fell into the lake and that the giant squid carried him back to the surface. At the end of every school year, graduated 7th years leave the school by sailing back across the lake.

Students from the Durmstrang Institute arrived at Hogwarts on their enchanted boat via the Black Lake. As part of the second task of the Tri-Wizard Tournament, the four champions Harry Potter, Fleur Delacour, Cedric Diggory, and Viktor Krum had to swim in the lake for sixty minutes to rescue something that was taken from them. Harry used Gillyweed to be able to breath underwater, while Cedric and Fleur used the Bubble-Head Charm, and Krum partially transfigured himself into a shark.