Øljusjøen is a lake in the municipalities of Hemsedal (in Buskerud county) and Lærdal (in Vestland county), Norway. The 8.45 km2 lake is located at an elevation of 1335 m above sea level. It sits about 15 km southeast of the village of Borgund and the European route E16 highway. The lake Eldrevatnet is 4 km to the north. The lake Juklevatnet and the mountain Høgeloft are both about 12 km to the northeast. Øljusjøen has a hydroelectric dam at the north end which directs water to a power station nearby. The water eventually goes into the Mørkedøla river.