Ełk Lake (Ełckie, Polish: Jezioro Ełckie, German: Lycker See; Lithuanian: Luko ežeras) is a fresh water lake in the Masurian Lake District of Poland's Warmia-Mazury Province to the west of the town of Ełk.

[4] The lake that was created by glacial action during the Pleistocene ice age and has a maximum surface area of 385 ha (950 acres).

[1][2] It is divided into two distinct parts, the northern ("small", Polish: Małe Ełckie) and southern ("large", Polish: Duże Ełckie), by a narrows spanned by a bridge.

[4] From the point of view of its recent eutrophication, there are three zones of the lake, northern, central (southern), and western.

[2] The two beaches in the central zone popular with the tourists visiting Ełk on the lakes east coast are suspected to now be among the primary sources of microplastics lake pollution.