Kolsvatnet is a lake in the municipality of Valle in Agder county, Norway. It is located about 14 kilometres (8.7 mi) southwest of the village of Valle and about 15 kilometres (9.3 mi) northwest of the village of Rysstad. The lake is located south of the lake Botnsvatnet, east of the mountain Urddalsknuten, and northeast of the lake Rosskreppfjorden. The lake has an area of 2.72 square kilometres (1.05 sq mi) and sits at an elevation of 1,034 metres (3,392 ft) above sea level.