Black Lake is a large body of water located in the Hogwarts School of Witchcraft and Wizardry grounds in the Harry Potter series. It is known for its dark, deep waters and is surrounded by a forest. The lake is home to various magical creatures, including the giant squid and the merpeople. The lake plays a significant role in several events throughout the series, including the Triwizard Tournament. It serves as a location for the second task, where champions must retrieve something valuable from its depths. Black Lake is also a place where students often gather for leisure and reflection.