| Ełk Lake | |
| Location: | Masurian Lake District |
| Coords: | 53.8067°N 22.3494°W |
| Basin Countries: | Poland |
| Pushpin Map: | Poland |
| Pushpin Map Alt: | Location of lakes in Poland |
Ełk Lake (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 adjacent to the town of Ełk.
The lake that was created by glacial action during the Pleistocene ice age and has a surface area is 3.82 square kilometres. Its average depth is 15m with 58.2m as a maximum. It is divided into two distinct parts, the northern ("small") and southern ("large"), by a narrows spanned by a bridge. Primarily fed by the Ełk River from the south west the lake discharges into Lake Sunowo at the north-west, and Lake Szarek at the south west.