The lakes are not evenly distributed; most are situated in the Baltic Highlands, which begin near the border with Poland on the southeast and extend northward along the border with Belarus to Latvia.
About 1,200 are supported only by groundwater and neither receive nor distribute any surface water.
These lake systems are major tourist attractions in Aukštaitija National Park and are popular with kayakers.
The lakes in and near the Molėtai district municipality are a weekend destination for many residents of Vilnius, who have summer houses and villas in the area.
The great majority of Lithuania's lakes formed after the Wisconsin glacier retreated.