Lake Maardu (; also 'Lake Liivakandi') is a lake in northern Estonia. It is located in the town of Maardu in Harju County. The village of Maardu with Maardu Manor is located on the southeastern side of the lake.
The lake has an area of . The lake has an average depth of and a maximum depth of . It is long, and its shoreline measures . It has a volume of . The lake is above sea level.
Lake Maardu was a natural body of water before 1894, when the landowner of Maardu Manor, Otto von Brevern, dug a ditch () to the sea and the lake was emptied. It was restored in 1939.