Lake Esrum (Danish: Esrum Sø) is the largest lake in Denmark by water volume and the second-largest lake by surface area, after lake Arresø. It is situated in the central part of North Zealand (the northeastern region of Zealand), straddling the boundaries of the municipalities Hillerød, Fredensborg, Helsingør and Gribskov, some 40 kilometres north of Copenhagen.
The lake covers 17 km2, Its length from north to south is 8.4 km and its maximum depth is 22 m. Its principal drainage is Esrum Å, a 10-km stream which passes Esrum Watermill and the remains of Esrum Abbey on its way to the Kattegat at Dronningmølle.
