Great Lake

**Harry Potter**: "*Underwater... Myrtle ... what lives in the lake, apart from the giant squid?*"
**Myrtle Warren**: "*Oh all sorts. I sometimes go down there ... sometimes don’t have any choice, if someone flushes my toilet when I’m not expecting it....*"
— Harry Potter and Myrtle Warren discussing the inhabitants of the Great Lake[src]

The **Great Lake** (alternatively known as the **Black Lake**) is a large body of water, freshwater and landlocked, located to the south of Hogwarts Castle. It is about half a mile in diameter and the castle's plumbing network drains into it.

## Description

### Inhabitants

The grounds of Hogwarts function partly as a nature reserve for magical creatures which have difficulty existing in Muggle-inhabited areas. There are Grindylows (vicious little water demons), Selkies (of a hardy Scottish strain) and a giant squid, which is semi-domesticated and permits students to tickle its tentacles on sunny days, when it basks in the shallows. The lake has a Bowtruckle Island.

### Temperature

The lake is often said to be very cold, but Viktor Krum was known to have swam in it, wearing nothing but swimming trunks, apparently not affected by the low temperature (although this was probably due to the fact that his school, Durmstrang, is located in a place that is even colder).

Lily Evans and her friends were also said to dangle their legs over the water, which could mean that there were no rules whilst they were in school against swimming in the lake.

## History

Every school year at Hogwarts, after the Hogwarts Express arrives at Hogsmeade station, Rubeus Hagrid (or a substitute) calls the first year students to follow him to the lake shore and the Hogwarts boats. Whereupon Hagrid occupies one boat and each other boat carries up to four students. The boats then self-propels across the lake to a dock under Hogwarts Castle as per tradition. At the start of the 1994–1995 school year, first year Dennis Creevey said he fell into the lake and the Giant Squid pushed him back into a boat.

Upon reaching the castle, Hagrid and the first years disembark and climb the stairs to the lawn, entering the castle through the front doors. First years then waited until summoned into the Great Hall to get Sorted into their houses. At the end of their first year, students take the boats back to Hogsmeade Station, while most older students ride down the lane in carriages.

At the end of every school year, graduating seventh years leave the school by sailing back across the lake.

### Saving the innocent

On 6 June 1994, Harry Potter, Hermione Granger and Sirius Black were attacked by Dementors on the shore of the lake. Harry tried to protect them by using Patronus Charm, but he did not succeed. Before he fainted he suddenly saw a person conjuring a corporeal Patronus on the opposite side of the lake. Later that night, after using Hermione's Time-Turner in Hospital Wing, they went back in time to save Black. Harry circled the lake and waited for the Dementors. Watching the events, he realised that he earlier saw himself and conjured a corporeal Patronus in deer form to flush the Dementors.

### Triwizard Tournament

Students from Durmstrang Institute arrived at Hogwarts on their enchanted boat via the Great Lake. As part of the Second Task of the Triwizard Tournament, the four champions Harry Potter, Fleur Delacour, and Cedric Diggory, and Viktor Krum had to swim in the lake for one hour 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.

### Dumbledore's Funeral

In 1997, Albus Dumbledore was laid to rest in a white tomb on the shores of the lake following his death in the Battle of the Astronomy Tower.

### Trevor's escape

At some point in his life, Trevor managed to escape from Neville and into the lake. Both pet and owner felt a sense of relief at this.