| Lake Ilmenak | |
| Coordinates: | 55.6801°N 27.1892°W |
| Pushpin Map: | Belarus |
| Pushpin Map Alt: | Location of the lake in Belarus. |
Lake Ilmenak (be|Возера Ільменак) is a lake in the Braslau Lakes National Park of northern Belarus. It lies about northeast of Braslau.
The lake is small and covers an area of with a length of . The maximum width is and the coastline is . The water volume is 0.61 mln m³ and the catchment area is . The greatest depth is . The slopes of the valley reach a height of, and are wooded in the south, west and north. The banks are low and sandy. Two streams flow into the lake.