The Black Lake is a large body of water to the south of the castle. It's about half a mile in diameter, and used to drain the school's plumbing network. As per tradition, first years sail across the lake to Hogwarts, led by Hagrid in boats. It's often cold, but students sometimes have their legs in the water, and some swim in it. The lake is home to a Giant Squid, grindylows, and a colony of Merpeople.
