Elfrather See is a lake in North Rhine-Westphalia, Germany. At an elevation of 30 m, its surface area is 0.5 square kilometres (0.19 sq mi).The Elfrather lake, popularly known as E for short-sea, is located in the north east of the city of Krefeld on the border of the Elfrath district. The lake was created from a disused gravel pit, which has been filled with groundwater.