Lake Yliki ( Yliki, Ancient Greek: á½Âûïú÷ Hylike, Latinised as Hylica) is a large natural lake of Boeotia, central Greece. Situated 8 km north of Thebes at 78 m elevation, it has been an important source of drinking water for the Athens agglomeration since 1958. It is surrounded by low mountains, which separate it from the drained Lake Copais.
The lake is home to several threatened endemic or near-endemic fish species: (IUCN Red List status shown)
Some scenes of French-singer Indila's music video "S.O.S" were filmed at the lake.