Lake Završnica (also Završniško lake) is accumulation lake, artificially dammed lake in valley Završnica under the mountain Stol in Karavanke. It is located near the village Moste in municipality Žirovnica. It is filled by a stream Završnica, which springs in Zelenica under Stol. The lake lies on altitude 640 meters, with surface of 2.5 ha and the bigest depth 10 meters. It is not allowed to swimm in the lake.

It was made in year 1914 for needs of accumulation water for hydroelectric power station Završnica, which was first public hydroelectric power station in Slovenia (for information: HE Završnica does not work anymore and whole water is redirected to HE Moste).

In lake are living brown trouts. rainbow trouts and graylings. Hunting graylings is prohibited.